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Sample records for arpo bibi steinberg

  1. 65th birthday Jack Steinberger

    ScienceCinema

    None

    2011-04-25

    Laudatio pour Jack Steinberger né le 25 mai 1921, à l'occasion de son 65me anniversaire et sa retraite officielle, pour sa précieuse collaboration au Cern. Néanmoins son principal activité continuera comme avant dans sa recherche au Cern. Plusieurs orateurs prennent la parole (p.ex. E.Picasso) pour le féliciter et lui rendre hommage

  2. The Media Do Matter: Comment on Steinberg and Monahan (2011)

    ERIC Educational Resources Information Center

    Brown, Jane D.

    2011-01-01

    Steinberg and Monahan's (2011) reanalysis of the Teen Media longitudinal survey of adolescents does not meet prevailing standards for propensity score analysis and therefore does not undermine the original conclusions of the Brown, L'Engle, Pardun, Guo, Kenneavy, and Jackson (2006) analysis. The media do matter in the sexual socialization of…

  3. Award for Distinguished Contributions to Research in Public Policy: Laurence Steinberg

    ERIC Educational Resources Information Center

    American Psychologist, 2009

    2009-01-01

    Laurence Steinberg, recipient of the Award for Distinguished Contributions to Research in Public Policy, is cited for his extraordinary impact on policy in juvenile justice and child labor and on research into the role of parent and peer relationships in the development of children and adolescents. His groundbreaking research is marked by a…

  4. Narrow Assessments Misrepresent Development and Misguide Policy: Comment on Steinberg, Cauffman, Woolard, Graham, and Banich (2009)

    ERIC Educational Resources Information Center

    Fischer, Kurt W.; Stein, Zachary; Heikkinen, Katie

    2009-01-01

    Intellectual and psychosocial functioning develop along complex learning pathways. Steinberg, Cauffman, Woolard, Graham, and Banich measured these two classes of abilities with narrow, biased assessments that captured only a segment of each pathway and created misleading age patterns based on ceiling and floor effects. It is a simple matter to…

  5. "Inside Transracial Adoption," by Gail Steinberg and Beth Hall. Book Review.

    ERIC Educational Resources Information Center

    Derman-Sparks, Louise

    2001-01-01

    Notes that Steinberg and Hall's book examines challenges and possibilities of transracial adoption, asserting that the work is the choice for white parents thinking about becoming or already in a transracial-adopted family, and for professionals working with parents and/or children in such families. Suggests that the book's only weakness stems…

  6. Lattice dynamics and electron-phonon interaction in Bi/Bi2Te3 (111) heteroepitaxial film

    NASA Astrophysics Data System (ADS)

    Huang, G. Q.; Li, B.

    2013-12-01

    Bi/Bi2Te3 (111) heteroepitaxial film is a novel system which combines two-dimensional and three-dimensional topological insulators. The lattice dynamical properties and the electron-phonon coupling in this heteroepitaxial film are calculated by including spin-orbit coupling from density functional perturbation theory. Full phonon dispersion curves are calculated and the zone-center Raman active modes are analyzed. There is a large mismatch in the phonon densities of states between ultrathin Bi deposited layers and Bi2Te3 substrate, which might have a significant improvement of thermoelectric performance of this system. The large electron-phonon coupling λ in Bi/Bi2Te3 heteroepitaxial film suggests that this system may hopefully become a topological superconductor.

  7. U-Pb geochronology and geochemistry of Bibi-Maryam pluton, eastern Iran: Implication for the late stage of the tectonic evolution of the Sistan Ocean

    NASA Astrophysics Data System (ADS)

    Delavari, Morteza; Amini, Sadraddin; Schmitt, Axel K.; McKeegan, Kevin D.; Mark Harrison, T.

    2014-07-01

    The Bibi-Maryam pluton crops out in the Sistan suture zone, eastern Iran. This pluton is a 1.5 × 2 km stock composed of leucocratic tonalite, granodiorite and granite. U-Pb zircon geochronology of a leucogranite indicates an emplacement age of 58.6 ± 2.1 Ma (95% confidence). The Bibi-Maryam rock suite is sodic with elevated Na2O/K2O (2.9 to 5.5), Sr/Y (15.6-62.2), La/Yb (13.3-22.2), and low MgO (0.86-1.81) abundances. It lacks significant Eu anomalies. Because of these geochemical characteristics, Bibi-Maryam rocks are similar to high-SiO2 adakites. Trace element modeling indicates that the Bibi-Maryam adakitic rocks could be produced by 5-8% non-modal batch partial melting from a source with composition of 95% N-MORB + 5% sediment in the presence of 35-40% amphibole + 5-10% garnet + 55-60% clinopyroxene + 1% apatite + 1% rutile. This source mineralogy is similar to hornblende eclogite or garnet amphibolites. Collectively, these data provide new constraints for the evolution of the Sistan suture zone and suggest that the Bibi-Maryam pluton formed via slab melting in an oceanic arc and pre-plate collision tectonic setting. This implies that the closure of the Sistan Ocean and Lut-Afghan continental blocks collision happened after the Bibi-Maryam emplacement at 58.6 ± 2.1 Ma.

  8. Size-controllable synthesis of Bi/Bi2O3 heterojunction nanoparticles using pulsed Nd:YAG laser deposition and metal-semiconductor-heterojunction-assisted photoluminescence

    NASA Astrophysics Data System (ADS)

    Patil, Ranjit A.; Wei, Mao-Kuo; Yeh, P.-H.; Liang, Jyun-Bo; Gao, Wan-Ting; Lin, Jin-Han; Liou, Yung; Ma, Yuan-Ron

    2016-02-01

    We synthesized Bi/Bi2O3 heterojunction nanoparticles at various substrate temperatures using the pulsed laser deposition (PLD) technique with a pulsed Nd:YAG laser. The Bi/Bi2O3 heterojunction nanoparticles consisted of Bi nanoparticles and Bi2O3 surface layers. The average diameter of the Bi nanoparticles and the thickness of the Bi2O3 surface layer are linearly proportional to the substrate temperature. The heterojunctions between the Bi nanoparticles and Bi2O3 surface layers, which are the metal-semiconductor heterojunctions, can strongly enhance the photoluminescence (PL) of the Bi/Bi2O3 nanoparticles, because the metallic Bi nanoparticles can provide massive free Fermi-level electrons for the electron transitions in the Bi2O3 surface layers. The enhancement of PL emission at room temperature by metal-semiconductor-heterojunctions make the Bi/Bi2O3 heterojunction nanoparticles potential candidates for use in optoelectronic nanodevices, such as light-emitting diodes (LEDs) and laser diodes (LDs).We synthesized Bi/Bi2O3 heterojunction nanoparticles at various substrate temperatures using the pulsed laser deposition (PLD) technique with a pulsed Nd:YAG laser. The Bi/Bi2O3 heterojunction nanoparticles consisted of Bi nanoparticles and Bi2O3 surface layers. The average diameter of the Bi nanoparticles and the thickness of the Bi2O3 surface layer are linearly proportional to the substrate temperature. The heterojunctions between the Bi nanoparticles and Bi2O3 surface layers, which are the metal-semiconductor heterojunctions, can strongly enhance the photoluminescence (PL) of the Bi/Bi2O3 nanoparticles, because the metallic Bi nanoparticles can provide massive free Fermi-level electrons for the electron transitions in the Bi2O3 surface layers. The enhancement of PL emission at room temperature by metal-semiconductor-heterojunctions make the Bi/Bi2O3 heterojunction nanoparticles potential candidates for use in optoelectronic nanodevices, such as light-emitting diodes

  9. Size-controllable synthesis of Bi/Bi2O3 heterojunction nanoparticles using pulsed Nd:YAG laser deposition and metal-semiconductor-heterojunction-assisted photoluminescence.

    PubMed

    Patil, Ranjit A; Wei, Mao-Kuo; Yeh, P-H; Liang, Jyun-Bo; Gao, Wan-Ting; Lin, Jin-Han; Liou, Yung; Ma, Yuan-Ron

    2016-02-14

    We synthesized Bi/Bi2O3 heterojunction nanoparticles at various substrate temperatures using the pulsed laser deposition (PLD) technique with a pulsed Nd:YAG laser. The Bi/Bi2O3 heterojunction nanoparticles consisted of Bi nanoparticles and Bi2O3 surface layers. The average diameter of the Bi nanoparticles and the thickness of the Bi2O3 surface layer are linearly proportional to the substrate temperature. The heterojunctions between the Bi nanoparticles and Bi2O3 surface layers, which are the metal-semiconductor heterojunctions, can strongly enhance the photoluminescence (PL) of the Bi/Bi2O3 nanoparticles, because the metallic Bi nanoparticles can provide massive free Fermi-level electrons for the electron transitions in the Bi2O3 surface layers. The enhancement of PL emission at room temperature by metal-semiconductor-heterojunctions make the Bi/Bi2O3 heterojunction nanoparticles potential candidates for use in optoelectronic nanodevices, such as light-emitting diodes (LEDs) and laser diodes (LDs). PMID:26804935

  10. Low Emissions Alternative Power (LEAP) Project Office Business Team of the Aeropropulsion Research Program Office (ARPO) Org. 0140

    NASA Technical Reports Server (NTRS)

    Buttler, Jennifer A.

    2004-01-01

    The program for which I am working at this summer is Propulsion and Power/Low Emissions Alternative Power (P&P/LEAP). It invests in a fundamental TRL 1-6 research and technology portfolio that will enable the future of: Alternative fuels and/or alternative propulsion systems, non-combustion (electric) propulsion systems. P&P/LEAP will identify and capitalize on the highest potential concepts generated both internal and external to the Agency. During my 2004 summer at NASA Glenn Research Center, I worked with my mentor Barbara Mader, in the Project Office with the Business Team completing various tasks for the project and personnel. The LEAP project is a highly matrixed organization. The Project Office is responsible for the goals advocacy and dollar (budget) of the LEAP project. The objectives of the LEAP Project are to discover new energy sources and develop unconventional engines and power systems directed towards greatly reduced emissions, enable new vehicle concepts for public mobility, new science missions and national security. The Propulsion and PowerLow Emissions Alternative Power directly supports the environmental, mobility, national security objectives of the Vehicle Systems Program and the Aeronautics Technology Theme. Technology deliverables include the demonstration through integrated ground tests, a constant volume combustor in an engine system, and UAV/small transport aircraft all electric power system. My mentor serves as a key member of the management team for the Aeropropulsion Research Program Office (ARPO). She has represented the office on numerous occasions, and is a member of a number of center-wide panels/teams, such as the Space management Committee and is chair to the Business Process Consolidation Team. She is responsible for the overall coordination of resources for the Propulsion and Power Project - from advocacy to implementation. The goal for my summer at NASA was to document processes and archive program documents from the past

  11. Kinetics of Spanish broom peroxidase obeys a Ping-Pong Bi-Bi mechanism with competitive inhibition by substrates.

    PubMed

    Pérez Galende, Patricia; Hidalgo Cuadrado, Nazaret; Kostetsky, Eduard Ya; Roig, Manuel G; Villar, Enrique; Shnyrov, Valery L; Kennedy, John F

    2015-11-01

    In plants, adverse conditions often induce an increase in reactive oxygen species (ROS) such as hydrogen peroxide (H2O2). H2O2 is reduced to water, and thus becomes detoxified by enzymes such as Cytisus multiflorus peroxidase (CMP). Here, the steady-state kinetics of the H2O2-supported oxidation of different organic substrates by CMP was investigated. Analysis of the initial rates vs. H2O2 and reducing substrate concentrations proved to be consistent with a substrate-inhibited Ping-Pong Bi-Bi reaction mechanism. The phenomenological approach expresses the peroxidase Ping-Pong mechanism in the form of the Michaelis-Menten equation and affords an interpretation of the effects in terms of the kinetic parameters [Formula: see text] , [Formula: see text] , kcat, [Formula: see text] , [Formula: see text] and of the microscopic rate constants, k1 and k3, of the shared three-step catalytic cycle of peroxidases. PMID:26416239

  12. Propensity Scoring and the Relationship between Sexual Media and Adolescent Sexual Behavior: Comment on Steinberg and Monahan (2011)

    ERIC Educational Resources Information Center

    Collins, Rebecca L.; Martino, Steven C.; Elliott, Marc N.

    2011-01-01

    Longitudinal research has demonstrated a link between exposure to sexual content in media and subsequent changes in adolescent sexual behavior, including initiation of intercourse and various noncoital sexual activities. Based on a reanalysis of one of the data sets involved, Steinberg and Monahan (2011) have challenged these findings. However,…

  13. [The terminal patient: Jewish religious law, the Steinberg report and the bioethical discourse in Israel].

    PubMed

    Barilan, Y Michael

    2003-07-01

    This article surveys key texts in contemporary orthodox Jewish law (Halakha) with regard to end-of-life decision making. The author proposes twelve principles that govern Jewish law in that matter. The article proceeds to examine the Steinberg report in the light of Halakha. Orthodox Judaism regards human life as a prime value, which is always beyond consideration of economical means or quality of life. The avoidance of suffering is the only justification to shorten the life of the sufferer, provided that the acts performed do not fall within the Halakhic definition of murder, namely active and direct action that shortens life. It is argued that the main challenge of bioethics in Israel is the bridging between the positive law of Halakha whose fundamental value is submission to God's will as manifested in Halakha, and the rationalism, universalism, and egalitarianism which constitute naturalistic ethics. This challenge may produce ideas such as the "clock machine". It is too early to know if this is a trickery, or genuine ethical creativity. PMID:12908395

  14. An alternate route for preparing deaf children for BiBi programs: the home language as L1 and cued speech for conveying traditionally spoken languages.

    PubMed

    Lasasso, C; Metzger, M

    1998-01-01

    This article focuses on nonsigning hearing parents of deaf children who share the goals of bilingual-bicultural (BiBi) programs for their child, opt for their home language to be their deaf child's first language (L1), and have questions about communication options (e.g., oral methods, manually coded English [MCE] systems, or Cued Speech) for conveying that language. We present research findings related to the effectiveness of MCE systems and Cued Speech for conveying English and developing deaf children's reading abilities. We compare the cueing of English and the signing of MCE systems in terms of theoretical and practical advantages. Finally, we suggest research needs. PMID:15579868

  15. Simulation and Interpretation of the BIBI Ratio CB (.), as a Function of Thermal Parameters of the Low Inertia Polyethylene Wall of Greenhouses

    NASA Astrophysics Data System (ADS)

    Bendimerad, S.; Mahdjoub, T.; Bibi-Triki, N.; Bessenouci, M. Z.; Draoui, B.; Bechar, H.

    The conventional agricultural tunnel greenhouse is highly widespread in Mediterranean countries, despite the shortcomings it presents, specifically the overheating during the day and the intense cooling at night. This can sometimes lead to an internal thermal inversion. The chapel-shaped glass greenhouse is relatively more efficient, but its evolution remains slow because of its investment cost and amortization. The thermal behavior of a greenhouse has often been studied, mainly during the night. In order to contribute to a better climatic management of the greenhouse, we proposed to develop a thermal analysis model. In this work, a ratio called BIBI was developed to characterize the covering material. This thermal evolution state depends on the degree of air-tightness of this covering material and its physical characteristics. It has to be transparent to solar rays, and must as well absorb and reflect infrared rays emitted by the soil. This leads to trapped solar rays, called the "greenhouse effect". In this paper we propose the modeling and analysis of the thermal behavior of the polyethylene (PE) wall of the experimental tunnel greenhouse.

  16. Depleted subcontinental lithospheric mantle and its tholeiitic melt metasomatism beneath NE termination of the Eger Rift (Europe): the case study of the Steinberg (Upper Lusatia, SE Germany) xenoliths

    NASA Astrophysics Data System (ADS)

    Kukuła, Anna; Puziewicz, Jacek; Matusiak-Małek, Magdalena; Ntaflos, Theodoros; Büchner, Jörg; Tietz, Olaf

    2015-12-01

    The ca. 30 Ma Steinberg basanite occurs at the NE termination of the Eger (Ohře) Rift in the NW Bohemian Massif, Central Europe, and belongs to the Cenozoic alkaline Central European Volcanic Province. The basanite hosts a suite of mantle xenoliths, most of which are harzburgites containing relatively magnesian olivine (Fo 90.5-91.6) and Al-poor (0.04-0.13 a pfu) orthopyroxene (mg# 0.90-0.92). Some of these harzburgites also contain volumetrically minor clinopyroxene (mg# 0.92-0.95, Al 0.03-0.13 a pfu) and have U-shaped LREE-enriched REE patterns. The Steinberg harzburgites are typical for the Lower Silesian - Upper Lusatian domain of the European subcontinental lithospheric mantle. They represent residual mantle that has undergone extensive partial melting and was subsequently affected by mantle metasomatism by mixed carbonatite-silicate melts. The Steinberg xenolith suite comprises also dunitic xenoliths affected by metasomatism by melt similar to the host basanite, which lowered the Fo content in olivine to 87.6 %. This metasomatism happened shortly before xenolith entrainment in the erupting lava. One of the xenoliths is a wehrlite (olivine Fo 73 %, clinopyroxene mg# 0.83-0.85, subordinate orthopyroxene mg# 0.76-0.77). Its clinopyroxene REE pattern is flat and slightly LREE-depleted. This wehrlite is considered to be a tholeiitic cumulate. One of the studied harzburgites contains clinopyroxene with similar trace element contents to those in wehrlite. This type of clinopyroxene records percolation of tholeiitic melt through harzburgite. The tholeiitic melt might be similar to Cenozoic continental tholeiites occurring in the Central European Volcanic Province (e.g., Vogelsberg, Germany).

  17. Changing the Context Is Important and Necessary, but Not Sufficient, for Reducing Adolescent Risky Sexual Behavior: A Reply to Steinberg (2015).

    PubMed

    Bryan, Angela D; Gillman, Arielle S; Hansen, Natasha S

    2016-07-01

    Starting school later, keeping adolescents busy with structured programming, and making free condoms available, as Steinberg (2015) suggests, are important and necessary steps, but they are simply not sufficient if the goal is reducing sexually transmitted infections and unplanned pregnancy. We agree that the current state of affairs, which in many schools involves sexuality education using programs that are not empirically supported, is unacceptable. However, abandoning sexuality education entirely would leave adolescents ill equipped to protect themselves. Despite the fact that current intervention technology is neither perfect nor optimally effective, there are empirically supported, school-based sexual risk reduction interventions that teach these skills and are readily available. In addition, even though we agree that structured afternoon programs for school-aged adolescents would reduce the opportunity for sexual risk behavior during the school years, such programs would not address the demographic reality of sexual risk that continues for adolescents and emerging adults far past the end of traditional secondary education. We believe Steinberg's suggestions are an excellent start and ought to be implemented. But complementary to this approach should be the use of existing empirically supported sexual risk reduction interventions and research into the development of even more effective interventions. PMID:27474139

  18. Steinberg ``AUDIOMAPS'' Music Appreciation-Via-Understanding: Special-Relativity + Expectations ``Quantum-Theory'': a Quantum-ACOUSTO/MUSICO-Dynamics (QA/MD)

    NASA Astrophysics Data System (ADS)

    Fender, Lee; Steinberg, Russell; Siegel, Edward Carl-Ludwig

    2011-03-01

    Steinberg wildly popular "AUDIOMAPS" music enjoyment/appreciation-via-understanding methodology, versus art, music-dynamics evolves, telling a story in (3+1)-dimensions: trails, frames, timbres, + dynamics amplitude vs. music-score time-series (formal-inverse power-spectrum) surprisingly closely parallels (3+1)-dimensional Einstein(1905) special-relativity "+" (with its enjoyment-expectations) a manifestation of quantum-theory expectation-values, together a music quantum-ACOUSTO/MUSICO-dynamics(QA/MD). Analysis via Derrida deconstruction enabled Siegel-Baez "Category-Semantics" "FUZZYICS"="CATEGORYICS ('TRIZ") Aristotle SoO DEduction , irrespective of Boon-Klimontovich vs. Voss-Clark[PRL(77)] music power-spectrum analysis sampling-time/duration controversy: part versus whole, shows QA/MD reigns supreme as THE music appreciation-via-analysis tool for the listener in musicology!!! Connection to Deutsch-Hartmann-Levitin[This is Your Brain on Music, (06)] brain/mind-barrier brain/mind-music connection is subtle/compelling/immediate!!!

  19. Bi{sub 3}In{sub 4}S{sub 10} and Bi{sub 14.7}In{sub 11.3}S{sub 38}: Two new bismuth sulfides with interesting Bi-Bi bonding

    SciTech Connect

    Yin Wenlong; Mei Dajiang; Yao, Jiyong; Fu, Peizhen; Wu, Yicheng

    2010-11-15

    Two new ternary bismuth chalcogenides, Bi{sub 3}In{sub 4}S{sub 10} and Bi{sub 14.7}In{sub 11.3}S{sub 38}, were synthesized from the reactions of binary sulfides via a two-step flux technique. Single-crystal X-ray diffraction analyses indicate that Bi{sub 3}In{sub 4}S{sub 10} crystallizes in the non-centrosymmetric space group Pm and Bi{sub 14.7}In{sub 11.3}S{sub 38} crystallizes in the centrosymmetric space group P2{sub 1}/m. Both compounds adopt three-dimensional frameworks. A distinct structural feature in the two structures is the presence of chains of Bi atoms with alternating short Bi-Bi bonds of around 3.1 A and longer distances of around 4.6 A. The optical band gaps of 1.42(2) eV for Bi{sub 3}In{sub 4}S{sub 10} and 1.45(2) eV for Bi{sub 14.7}In{sub 11.3}S{sub 38} were deduced from the diffuse reflectance spectra. - Graphical abstract: Two new bismuth sulfides Bi{sub 3}In{sub 4}S{sub 10} and Bi{sub 14.7}In{sub 11.3}S{sub 38} have been synthesized and characterized. The figure is the arrangement of Bi1 atoms along the b direction with alternating short and long distances (A) in Bi{sub 3}In{sub 4}S{sub 10}. Display Omitted

  20. Synthesis and Biological Activity of Manganese (II) Complexes of Phthalic and Isophthalic Acid: X-Ray Crystal Structures of [Mn(ph)(Phen)(2)(H(2)O)]. 4H(2)O, [Mn(Phen)(2)(H(2)O)(2)](2)(Isoph)(2)(Phen). 12H(2)O and {[Mn(Isoph)(bipy)](4). 2.75biby}(n)(phH(2) = Phthalic Acid; isoph = Isophthalic Acid; phen = 1,10-Phenanthroline; bipy = 2,2-Bipyridine).

    PubMed

    Devereux, M; McCann, M; Leon, V; Geraghty, M; McKee, V; Wikaira, J

    2000-01-01

    Manganese(II) acetate reacts with phthalic acid (phH(2)) to give [Mn(ph)].0.5H(2)O (1). Reaction of 1 with 1,10-phenanthroline produces [Mn(ph)(phen)].2H(2)O (2) and [Mn(ph)(phen)(2)(H(2)O)].4H(2)O (3). Reaction of isophthalic acid (isophH(2)) with manganese(II) acetate results in the formation of [Mn(isoph)].2H(2)O (4). The addition of the N,N-donor ligands 1,10-phenanthroline or 2,2'-bipyridine to 4 leads to the formation of [Mn(2) (isoph)(2)(phen)(3))].4H(2)O (5), [(Mn(phen)(2)(H(2)O)(2)](2)(isoph)(2)(phen).12H(2)O (6) and {[Mn(isoph)(bipy)](4).2.75 biby}(n) (7), respectively. Molecular structures of 3, 6 and 7 were determined crystallographically. In 3 the phthalate ligand is bound to the manganese via just one of its carboxylate groups in a monodentate mode with the remaining coordination sites filled by four phenanthroline nitrogen and one water oxygen atoms. In 6 the isophthalates are uncoordinated with the octahedral manganese center ligated by two phenanthrolines and two waters. In 7 the Isophthalate ligands act as bridges resulting in a polymeric structure. One of the carboxylate groups is chelating a single manganese with the other binding two metal centres in a bridging bidentate mode. The phthalate and isophthalate complexes, the metal free ligands and a number of simple manganes salts were each tested for their ability, to inhibit the growth of Candida albicans. Only the "metal free" 1,10-phenanthroline and its manganese complexes were found to be active. PMID:18475957

  1. Synthesis and Biological Activity of Manganese (II) Complexes of Phthalic and Isophthalic Acid: X-Ray Crystal Structures of [Mn(ph)(Phen)2(H2O)]· 4H2O, [Mn(Phen)2(H2O)2]2(Isoph)2(Phen)· 12H2O and {[Mn(Isoph)(bipy)]4· 2.75biby}n(phH2 = Phthalic Acid; isoph = Isophthalic Acid; phen = 1,10-Phenanthroline; bipy = 2,2-Bipyridine)

    PubMed Central

    McCann, Malachy; Leon, Vanessa; Geraghty, Majella; McKee, Vickie; Wikaira, Jan

    2000-01-01

    Manganese(II) acetate reacts with phthalic acid (phH2) to give [Mn(ph)]·0.5H2O (1). Reaction of 1 with 1,10-phenanthroline produces [Mn(ph)(phen)]·2H2O (2) and [Mn(ph)(phen)2(H2O)]·4H2O (3). Reaction of isophthalic acid (isophH2) with manganese(II) acetate results in the formation of [Mn(isoph)]·2H2O (4). The addition of the N,N-donor ligands 1,10-phenanthroline or 2,2'-bipyridine to 4 leads to the formation of [Mn2 (isoph)2(phen)3)]·4H2O (5), [(Mn(phen)2(H2O)2]2(isoph)2(phen)·12H2O (6) and {[Mn(isoph)(bipy)]4·2.75 biby}n (7), respectively. Molecular structures of 3, 6 and 7 were determined crystallographically. In 3 the phthalate ligand is bound to the manganese via just one of its carboxylate groups in a monodentate mode with the remaining coordination sites filled by four phenanthroline nitrogen and one water oxygen atoms. In 6 the isophthalates are uncoordinated with the octahedral manganese center ligated by two phenanthrolines and two waters. In 7 the Isophthalate ligands act as bridges resulting in a polymeric structure. One of the carboxylate groups is chelating a single manganese with the other binding two metal centres in a bridging bidentate mode. The phthalate and isophthalate complexes, the metal free ligands and a number of simple manganes salts were each tested for their ability, to inhibit the growth of Candida albicans. Only the “metal free” 1,10-phenanthroline and its manganese complexes were found to be active. PMID:18475957

  2. Jack Steinberger: Memories of the PS and of LEP

    NASA Astrophysics Data System (ADS)

    Tsesmelis, Emmanuel

    2012-03-01

    This contribution, a personal recollection by the author, is part of a special issue - CERN's accelerators, experiments and international integration 1959-2009. Guest Editor: Herwig Schopper [Schopper, Herwig. 2011. Editorial. Eur. Phys. J. H 36: 437

  3. Authors' Rejoinder to Respondents (Shulman, Steinberg, & Piquero, 2013)

    ERIC Educational Resources Information Center

    Males, Mike A.; Brown, Elizabeth A.

    2014-01-01

    Respondents, in "A Mistaken Account of the Age-Crime Curve: Response to Males and Brown," dispute our finding that virtually all of the discrepancy in violent crime rates between adolescents/emerging adults versus older adults is explained not by young age per se but by higher poverty levels among the young. Our rejoinder argues that…

  4. Steinberg ``AUDIOMAPS" Music Appreciation-Via-Understanding: Special-Relativity + Expectations "Quantum-Theory": a Quantum-ACOUSTO/MUSICO-Dynamics (QA/MD)

    NASA Astrophysics Data System (ADS)

    Steinberg, R.; Siegel, E.

    2010-03-01

    ``AUDIOMAPS'' music enjoyment/appreciation-via-understanding methodology, versus art, music-dynamics evolves, telling a story in (3+1)-dimensions: trails, frames, timbres, + dynamics amplitude vs. music-score time-series (formal-inverse power- spectrum) surprisingly closely parallels (3+1)-dimensional Einstein(1905) special-relativity ``+'' (with its enjoyment- expectations) a manifestation of quantum-theory expectation- values, together a music quantum-ACOUSTO/MUSICO-dynamics (QA/MD). Analysis via Derrida deconstruction enabled Siegel- Baez ``Category-Semantics'' ``FUZZYICS''=``CATEGORYICS (``SON of 'TRIZ") classic Aristotle ``Square-of-Opposition" (SoO) DEduction-logic, irrespective of Boon-Klimontovich versus Voss- Clark[PRL(77)] music power-spectrum analysis sampling- time/duration controversy: part versus whole, shows that ``AUDIOMAPS" QA/MD reigns supreme as THE music appreciation-via- analysis tool for the listener in musicology!!! Connection to Deutsch-Hartmann-Levitin[This is Your Brain on Music,(2006)] brain/mind-barrier brain/mind-music connection is both subtle and compelling and immediate!!!

  5. COMPARISON OF TWO INDICES OF BENTHIC COMMUNITY CONDITION IN CHESAPEAKE BAY

    EPA Science Inventory

    The Chesapeake Benthic Index of Biotic Integrity (B-IBI) and the EMAP-VP Benthic Index were applied to samples from 239 sites in Chesapeake Bay. The B-IBI weights several community measures equally and uses a simple scoring system while the EMAP-VP Benthic Index uses discriminant...

  6. Predicting biological condition in southern California streams

    USGS Publications Warehouse

    Brown, Larry R.; May, Jason T.; Rehn, Andrew C.; Ode, Peter R.; Waite, Ian R.; Kennen, Jonathan G.

    2012-01-01

    As understanding of the complex relations among environmental stressors and biological responses improves, a logical next step is predictive modeling of biological condition at unsampled sites. We developed a boosted regression tree (BRT) model of biological condition, as measured by a benthic macroinvertebrate index of biotic integrity (BIBI), for streams in urbanized Southern Coastal California. We also developed a multiple linear regression (MLR) model as a benchmark for comparison with the BRT model. The BRT model explained 66% of the variance in B-IBI, identifying watershed population density and combined percentage agricultural and urban land cover in the riparian buffer as the most important predictors of B-IBI, but with watershed mean precipitation and watershed density of manmade channels also important. The MLR model explained 48% of the variance in B-IBI and included watershed population density and combined percentage agricultural and urban land cover in the riparian buffer. For a verification data set, the BRT model correctly classified 75% of impaired sites (B-IBI < 40) and 78% of unimpaired sites (B-IBI = 40). For the same verification data set, the MLR model correctly classified 69% of impaired sites and 87% of unimpaired sites. The BRT model should not be used to predict B-IBI for specific sites; however, the model can be useful for general applications such as identifying and prioritizing regions for monitoring, remediation or preservation, stratifying new bioassessments according to anticipated biological condition, or assessing the potential for change in stream biological condition based on anticipated changes in population density and development in stream buffers.

  7. Perminalized Alethopteris from the Upper Pennsylvanian of Ohio and Illinois

    SciTech Connect

    Mickle, J.E.; Rothwell, G.W.

    1982-03-01

    Fern-like foliage referable to Alethopteris Steinberg has been discovered in coal balls of Late Pennsylvanian age from near Staubenville, Ohio, and Berryville, Illinois. Pinnule morphology is described from specimens preserved on coal-ball surfaces.

  8. What's In a Proton?

    ScienceCinema

    Brookhaven Lab

    2010-01-08

    Physicist Peter Steinberg explains that fundamental particles like protons are themselves made up of still smaller particles called quarks. He discusses how new particles are produced when quarks are liberated from protons...a process that can be observed

  9. What's In a Proton?

    SciTech Connect

    Brookhaven Lab

    2009-07-08

    Physicist Peter Steinberg explains that fundamental particles like protons are themselves made up of still smaller particles called quarks. He discusses how new particles are produced when quarks are liberated from protons...a process that can be observed

  10. 75 FR 80796 - Correction to Proposed Methodology for Respondent Selection in Antidumping Proceedings; Request...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-23

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE... of Commerce. FOR FURTHER INFORMATION CONTACT: Shauna Biby, Senior Import Policy Analyst, Office of Policy, Import Administration, U.S. Department of Commerce, 14th Street and Constitution Avenue,...

  11. Application of the benthic index of biotic integrity to environmental monitoring in Chesapeake Bay.

    PubMed

    Llansó, Roberto J; Dauer, Daniel M; Vølstad, Jon H; Scott, Lisa C

    2003-01-01

    The Chesapeake Bay benthic index of biotic integrity (B-IBI) was developed to assess benthic community health and environmental quality in Chesapeake Bay. The B-IBI provides Chesapeake Bay monitoring programs with a uniform tool with which to characterize bay-wide benthic community condition and assess the health of the Bay. A probability-based design permits unbiased annual estimates of areal degradation within the Chesapeake Bay and its tributaries with quantifiable precision. However, of greatest interest to managers is the identification of problem areas most in need of restoration. Here we apply the B-IBI to benthic data collected in the Bay since 1994 to assess benthic community degradation by Chesapeake Bay Program segment and water depth. We used a new B-IBI classification system that improves the reliability of the estimates of degradation. Estimates were produced for 67 Chesapeake Bay Program segments. Greatest degradation was found in areas that are known to experience hypoxia or show toxic contamination, such as the mesohaline portion of the Potomac River, the Patapsco River, and the Maryland mainstem. Logistic regression models revealed increased probability of degraded benthos with depth for the lower Potomac River, Patapsco River. Nanticoke River, lower York River, and the Maryland mainstem. Our assessment of degradation by segment and water depth provided greater resolution of relative condition than previously available, and helped define the extent of degradation in Chesapeake Bay. PMID:12620013

  12. Lipase catalysed synthesis of cetyl oleate using ultrasound: Optimisation and kinetic studies.

    PubMed

    Khan, Nishat R; Jadhav, Sachin V; Rathod, Virendra K

    2015-11-01

    The current paper exemplifies the application of ultrasound technology to enzymatic synthesis of a cosmetic emollient ester, cetyl oleate. Fermase CALB™10000, a commercial Candida antarctica lipase B was used as a catalyst to accomplish the ultrasound supported synthesis. Multiple process parameters like reaction time, temperature, enzyme dose, alcohol to acid molar ratio, ultrasound power, frequency and speed of agitation were optimised. Maximum conversion of ∼95.96% was discerned at optimum conditions, i.e., 60°C temperature, 5% enzyme dose, 2:1 alcohol:acid ratio, 60 W ultrasound power, 25 kHz ultrasound frequency, 80% duty cycle and 80 rpm speed of agitation after purification steps. It was observed that the reaction reached equilibrium in a short duration of 30 min under the optimised conditions. This was considerably lesser than the time required for attaining equilibrium in conventional mechanical stirring method which was over 2h. Bisubstrate kinetic models like random bi-bi, ping pong bi-bi and ordered bi-bi were applied to the experimental data to determine initial rates and other kinetic parameters. Ordered bi-bi model showed the best fit with kinetic parameters, Vmax=0.029 M/min/gcatalyst, KA=0.00001 M, KB=4.8002 M, KiA=0.00014 M, KiB=3.7914 M & SSE=0.00022 for enzymatic cetyl oleate synthesis under ultrasound irradiation with inhibition by both acid and alcohol at high concentrations. PMID:25913878

  13. [Wounds caused by projectiles of pressure guns in children].

    PubMed

    Barreras-Salcedo, J I; Avila-Vergara, M A

    1993-05-01

    The present study is a survey to analyze the actual situation of the wounds produced by bibi-guns, concerning the damage produced, kind of surgical procedure, clinical evolution, and some general characteristics of the population on study. During a period of two years from May 1990 to May 1992 at the General Hospital of Culiacan, Sin. Six patients from the Pediatric Surgery Department with a diagnosis of wound produced by bibi-guns were studied. All patients required surgical treatment with general anesthesia. The average age of patients was 5.8 +/- 1.5 years, five male and one female; wounds were produced accidentally in four cases and two in a guns-game. The severity of the injury was evaluated, and in two cases their internal injury laid in danger the life of patient. No deaths occurred. PMID:8504003

  14. What's up, Billy Jo? Deaf children and bilingual-bicultural instruction in east-central Texas.

    PubMed

    Andrews, J F; Ferguson, C; Roberts, S; Hodges, P

    1997-03-01

    Seven deaf children attended a bilingual-bicultural (bi-bi) prekindergarten, kindergarten, and first grade from 1993 to 1996 in an east-central Texas public school. The children had diverse backgrounds (African American, Hispanic, White) and various intellectual, cognitive, and linguistic abilities. We detail the backgrounds of the seven children and their families and describe three bi-bi classrooms. We present standardized test scores on cognition (Bracken Test of Basic Concepts) and academic achievement (Stanford Achievement Test, 9th edition, and Woodcock-Johnson Psycho-Educational Battery). When, with one exception, the children completed first grade, they all tested at grade level. (The exception was a younger child who had only completed kindergarten but who nonetheless tested at the first-grade level). We interpret our findings in light of theories of first- and second-language acquisition and discuss the feasibility of establishing bi-bi programs in areas where no large Deaf community exists. We also note our plans to evaluate the seven children again, at the end of second grade in spring 1997. PMID:9127497

  15. 19 Urban Questions: Teaching in the City. Second Edition. Counterpoints: Studies in Postmodern Theory of Education, Vol. 215

    ERIC Educational Resources Information Center

    Steinberg, Shirley R., Ed

    2010-01-01

    The second edition of "19 Urban Questions: Teaching in the City" adds new questions to those in the original volume. Continuing the developing conversation in urban education, the book is provocative in style and rich in detail. Emphasizing the complexity of urban education, Shirley R. Steinberg and the authors ask direct questions about what…

  16. The Other Side of the Story: Israeli and Palestinian Teachers Write a History Textbook Together

    ERIC Educational Resources Information Center

    Steinberg, Shoshana; Bar-On, Dan

    2009-01-01

    In this essay, Shoshana Steinberg and Dan Bar-On present the work of a team of Israeli and Palestinian teachers who developed a history textbook that includes both groups' narratives of the same events side by side. These teachers then tested the effects of its use in both Israeli and Palestinian classrooms; for the first time, students on each…

  17. Will There Always be an English?

    ERIC Educational Resources Information Center

    Henry, George H.

    1972-01-01

    A critical review of English Education Today," edited by L.S. Josephs and E. R. Steinberg, which is more a review of English curriculum, the directions, philosophies, and problems in English instruction, with emphasis on the need to think critically and innovatively. (JB)

  18. Parental Relationships, Autonomy, and Identity Processes of High School Students

    ERIC Educational Resources Information Center

    Mullis, Ronald L.; Graf, Shruti Chatterjee; Mullis, Ann K.

    2009-01-01

    To examine the interrelations among parental relationships, emotional autonomy, and identity statuses, the authors asked 234 (105 male, 129 female) high school students to complete the Parental Bonding Scale (G. Parker, H. Tupling, & L. B. Brown, 1979), Emotional Autonomy Scale (L. D. Steinberg & S. B. Silverberg, 1986), and Extended Objective…

  19. Adolescent Development and the Regulation of Youth Crime

    ERIC Educational Resources Information Center

    Scott, Elizabeth S.; Steinberg, Laurence

    2008-01-01

    Elizabeth Scott and Laurence Steinberg explore the dramatic changes in the law's conception of young offenders between the end of the nineteenth century and the beginning of the twenty-first. At the dawn of the juvenile court era, they note, most youths were tried and punished as if they were adults. Early juvenile court reformers argued strongly…

  20. In praise of weakness

    NASA Astrophysics Data System (ADS)

    Steinberg, Aephraim; Feizpour, Amir; Rozema; Mahler; Hayat

    2013-03-01

    Quantum physics is being transformed by a radical new conceptual and experimental approach known as weak measurement that can do everything from tackling basic quantum mysteries to mapping the trajectories of photons in a Young's double-slit experiment. Aephraim Steinberg, Amir Feizpour, Lee Rozema, Dylan Mahler and Alex Hayat unveil the power of this new technique.

  1. 410th Brookhaven Lecture

    ScienceCinema

    Peter Steinberg

    2010-09-01

    In a lecture titled "Hotter, Denser, Faster, Smaller...and Nearly Perfect: What's the Matter at RHIC?", Steinberg discusses the basic physics of the quark-gluon plasma and BNL's Relativistic Heavy Ion Collider, with a focus on several intriguing results from RHIC's recently ended PHOBOS experiment.

  2. Designing across Ages: Multi-Agent-Based Models and Learning Electricity

    ERIC Educational Resources Information Center

    Sengupta, Pratim

    2009-01-01

    Electricity is regarded as one of the most challenging topics for students at all levels--middle school--college (Cohen, Eylon, & Ganiel, 1983; Belcher & Olbert, 2003; Eylon & Ganiel, 1990; Steinberg et al., 1985). Several researchers have suggested that naive misconceptions about electricity stem from a deep incommensurability (Slotta & Chi,…

  3. Emotional Autonomy versus Susceptibility to Peer Pressure: A Case Study of Hong Kong Adolescent Students

    ERIC Educational Resources Information Center

    Chan, Kwok-Wai; Chan, Siu-Mui

    2008-01-01

    A questionnaire consisting of two scales was administered to 550 Hong Kong secondary students to examine their emotional autonomy and susceptibility to peer pressure. Emotional autonomy was studied by the scale (EAS) developed by Steinberg and Silverberg (1986) and susceptibility to peer pressure was studied by the scale developed by Sim and Koh…

  4. King of Cool

    ERIC Educational Resources Information Center

    Freado, Mark; Van Bockern, Steve

    2010-01-01

    Many teenagers get involved in criminal activity. This tendency is so pervasive that psychologist Terrie Moffitt, one of the world's leading experts on the development of antisocial behavior, has described delinquent behavior as a normal part of teenager life (Scott & Steinberg, 2008). Adults, even those in the justice system, are often at a loss…

  5. Diabetes - foot ulcers

    MedlinePlus

    ... 33. Kim PJ, Steinberg JS. Complications of the diabetic foot. Endocrinol Metab Clin N Am. 2013;42:833-847. PMID: 24286952 www.ncbi.nlm.nih.gov/pubmed/24286952 . Read More Diabetes Diabetes and nerve damage Leg or foot amputation Type 1 diabetes Type 2 diabetes Patient Instructions Diabetes and ...

  6. Relationships between Adolescent Sexual Outcomes and Exposure to Sex in Media: Robustness to Propensity-Based Analysis

    ERIC Educational Resources Information Center

    Collins, Rebecca L.; Martino, Steven C.; Elliott, Marc N.; Miu, Angela

    2011-01-01

    Adolescent sexual health is a substantial problem in the United States, and two recent studies have linked adolescent sexual behavior and/or outcomes to youths' exposure to sex in the media. Both studies had longitudinal survey designs and used covariate-adjusted regression analysis. Steinberg and Monahan (2011) reanalyzed data from one of these…

  7. Reconciling the Complexity of Human Development with the Reality of Legal Policy: Reply to Fischer, Stein, and Heikkinen (2009)

    ERIC Educational Resources Information Center

    Steinberg, Laurence; Cauffman, Elizabeth; Woolard, Jennifer; Graham, Sandra; Banich, Marie

    2009-01-01

    The authors respond to both the general and specific concerns raised in Fischer, Stein, and Heikkinen's commentary on their article (Steinberg, Cauffman, Woolard, Graham, & Banich), in which they drew on studies of adolescent development to justify the American Psychological Association's positions in two Supreme Court cases involving the…

  8. Adolescents' Perceptions of Parental Goals, Practices, and Styles in Relation to Their Motivation and Achievement

    ERIC Educational Resources Information Center

    Spera, Christopher

    2006-01-01

    The current study examines research questions proposed by an expanded version of Darling and Steinberg's contextual model of parenting. Using a sample of 184 adolescents, the analyses indicated that adolescents' perceptions of parental educational goals and values were related positively and significantly to their reports of parental school…

  9. Acts of God - The Unnatural History of Natural Disaster in America

    NASA Astrophysics Data System (ADS)

    Steinberg, Ted

    2003-05-01

    With the exception of the 9/11 disaster, the top ten most costly catastrophes in U.S. history have all been natural disasters--five of them hurricanes--and all have occurred since 1989. Why this tremendous plague on our homes? In Acts of God , environmental historian Ted Steinberg explains that much of the death and destruction has been well within the realm of human control. Steinberg exposes the fallacy of seeing such calamities as simply random events. Beginning with the 1886 Charleston and 1906 San Francisco earthquakes, and continuing to the present, Steinberg explores the unnatural history of natural calamity, the decisions of business leaders and government officials that have paved the way for the greater losses of life and property, especially among those least able to withstand such blows--America's poor, elderly, and minorities. Seeing nature or God as the primary culprit, Steinberg argues, has helped to hide the fact that some Americans are better protected from the violence of nature than their counterparts lower down the socioeconomic ladder. Sure to provoke discussion, Acts of God is a call to action that must be heard. "A sobering lesson in humanity's vulnerability to extreme climatic events, especially the impoverished farmer and the urban poor."--The Los Angeles Times Book Review

  10. Beyond Authoritarianism: A Cultural Perspective on Asian American Parenting Practices.

    ERIC Educational Resources Information Center

    Chao, Ruth K.

    A study was conducted to determine Asian American conceptualizations of parenting, focusing on socialization goals, parenting style, and parenting practices related to schooling, aspects of parental influences discussed by D. Darling and L. Steinberg (1993). It was suggested that the standard conceptualizations of parenting style, those of D.…

  11. Literacy Update. Volume 18, Number 2

    ERIC Educational Resources Information Center

    Steinberg, Jon, Ed.

    2009-01-01

    This newsletter, published five times a year, features articles on issues of concern to adult, family, and youth literacy practitioners, as well as recommended resources, announcements, and teaching strategies. This issue contains: (1) Using a License to Drive Improvement: Professional Development in Massachusetts (Jon Steinberg); (2) Building…

  12. Further Thoughts on "How Task Features Impact Evidence from Assessments Embedded in Simulations and Games"

    ERIC Educational Resources Information Center

    Oliveri, María Elena; Khan, Saad

    2014-01-01

    María Oliveri, and Saad Khan write that the article: "How Task Features Impact Evidence from Assessments Embedded in Simulations and Games" provided helpful illustrations regarding the implementation of evidence-centered assessment design (Mislevy & Haertel, 2006; Mislevy, Steinberg, & Almond, 1999) with games and simulations.…

  13. Review of Pearson Test of English Academic: Building an Assessment Use Argument

    ERIC Educational Resources Information Center

    Wang, Huan; Choi, Ikkyu; Schmidgall, Jonathan; Bachman, Lyle F.

    2012-01-01

    This review departs from current practice in reviewing tests in that it employs an "argument-based approach" to test validation to guide the review (e.g. Bachman, 2005; Kane, 2006; Mislevy, Steinberg, & Almond, 2002). Specifically, it follows an approach to test development and use that Bachman and Palmer (2010) call the process of "assessment…

  14. Academic Value of Non-Academics: The Case for Keeping Extracurriculars

    ERIC Educational Resources Information Center

    Kronholz, June

    2012-01-01

    A growing body of research says there is a link between afterschool activities and graduating from high school, going to college, and becoming a responsible citizen. Temple University psychologist Laurence Steinberg, whose book, "You and Your Adolescent: The Essential Guide for Ages 10-25," discusses afterschool activities. He suggested two more…

  15. Parental Characteristics, Ecological Factors, and the Academic Achievement of African American Males

    ERIC Educational Resources Information Center

    Hines, Erik M.; Holcomb-McCoy, Cheryl

    2013-01-01

    Parental characteristics, ecological factors, and the academic achievement of African American male high school students were examined. One hundred fifty-three 11th and 12th grade African American males completed the Parenting Style Index (Steinberg, Lamborn, Darling, Mounts, & Dornbusch, 1994) and a demographic questionnaire. Results…

  16. Selling Out (In) Sport Management: Practically Evaluating the State of the American (Sporting) Union

    ERIC Educational Resources Information Center

    Wiest, Amber; King-White, Ryan

    2013-01-01

    When teaching in Sport Management programs professors are often forced to respond to the actions and teachings of professionals in the field. According to the study by Kincheloe & Steinberg many of these normalized and, indeed celebrated, behaviors are actions that are part and parcel of the "recovery movement" which (re)inscribe new…

  17. Autonomy, Educational Plans, and Self-Esteem in Institution-Reared and Home-Reared Teenagers in Estonia

    ERIC Educational Resources Information Center

    Tulviste, Tiia

    2011-01-01

    The study examines autonomy, self-esteem, and educational plans for the future of 109 institution-reared and 106 home-reared teenagers (15-19 years). Teenagers were asked to complete the Teen Timetable Scale (Feldman & Rosenthal), two Emotional Autonomy Scales (Steinberg & Silverberg), the Rosenberg Self-Esteem Scale, and answer questions about…

  18. Groups graded by root systems and property (T)

    PubMed Central

    Ershov, Mikhail; Jaikin-Zapirain, Andrei; Kassabov, Martin; Zhang, Zezhou

    2014-01-01

    We establish property (T) for a large class of groups graded by root systems, including elementary Chevalley groups and Steinberg groups of rank at least 2 over finitely generated commutative rings with 1. We also construct a group with property (T) which surjects onto all finite simple groups of Lie type and rank at least two. PMID:25425669

  19. Youth Violence: Do Parents and Families Make a Difference?

    ERIC Educational Resources Information Center

    Steinberg, Laurence

    2000-01-01

    This article is an adaptation of the authors statement to the U.S. House of Representatives Bipartisan Working Group on Youth Violence on September 15, 1999. Specifically, the Working Group asked Dr. Steinberg, an adolescent behavior researcher, to address issues concerning the role of parents and families in the genesis and prevention of youth…

  20. The MA in Writing at DePaul University

    ERIC Educational Resources Information Center

    Clary-Lemon, Jennifer; Vandenberg, Peter

    2006-01-01

    While discussion about the nature and function of the PhD has flourished for years in the broad context of English studies (Bérubé; Lunsford et al.; Nelson) and for more than a decade now in rhetoric and composition (Brown, Meyer, and Enos; North; Young and Steinberg), the Master's degree has attracted scant attention. No doubt this traces to a…

  1. Joe L. Kincheloe: Genies and Wishes--A Review of "Key Works in Critical Pedagogy"

    ERIC Educational Resources Information Center

    Ali-Khan, Carolyne; Siry, Christina

    2012-01-01

    We review "Key Works in Critical Pedagogy: Joe L. Kincheloe" edited by Kecia Hayes, Shirley R. Steinberg and Kenneth Tobin, which gathers the seminal works of Joe. L. Kincheloe and pairs them with contemporary scholars who respond to and push forward Kincheloe's work. The chapters of "Key Works in Critical Pedagogy" are arranged to begin with…

  2. The Development of Reproductive Strategy in Females: Early Maternal Harshness [right arrow] Earlier Menarche [right arrow] Increased Sexual Risk Taking

    ERIC Educational Resources Information Center

    Belsky, Jay; Steinberg, Laurence; Houts, Renate M.; Halpern-Felsher, Bonnie L.

    2010-01-01

    To test a proposition central to J. Belsky, L. Steinberg, and P. Draper's (1991) evolutionary theory of socialization--that pubertal maturation plays a role in linking early rearing experience with adolescent sexual risk taking (i.e., frequency of sexual behavior) and, perhaps, other risk taking (e.g., alcohol, drugs, delinquency)--the authors…

  3. 75 FR 51276 - National Institute of Mental Health; Notice of Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-19

    ... public as indicated below, with attendance limited to space available. Individuals who plan to attend and... of NIMH Director's report and discussion on NIMH program and policy issues. Place: National.... ] Contact Person: Jane A. Steinberg, PhD, Director, Division of Extramural Activities, National Institute...

  4. The development of the action potential mechanism of amphibian neurons isolated in culture.

    PubMed

    Spitzer, N C; Lamborghini, J E

    1976-05-01

    Nerve and muscle cells differentiated morphologically, in cultures of dissociated cells prepared from amphibian neural plate and underlying mesoderm (Xenopus laevis, Nieuwkoop and Faber stage 15). Cultures were grown in a defined medium containing sterile Steinberg's salt solution and 0.1% bovine serum albumin, and maintained for periods up to 5 days. PMID:1064036

  5. The development of the action potential mechanism of amphibian neurons isolated in culture.

    PubMed Central

    Spitzer, N C; Lamborghini, J E

    1976-01-01

    Nerve and muscle cells differentiated morphologically, in cultures of dissociated cells prepared from amphibian neural plate and underlying mesoderm (Xenopus laevis, Nieuwkoop and Faber stage 15). Cultures were grown in a defined medium containing sterile Steinberg's salt solution and 0.1% bovine serum albumin, and maintained for periods up to 5 days. Images PMID:1064036

  6. Premature Dissemination of Advice Undermines Our Credibility as Scientists: Reply to Brown (2011) and to Collins, Martino, and Elliott (2011)

    ERIC Educational Resources Information Center

    Steinberg, Laurence; Monahan, Kathryn C.

    2011-01-01

    In our reanalysis of data from the Brown et al. (2006) study (Steinberg & Monahan, 2011), we found no support for the contention that adolescents' exposure to sexy media content hastens their sexual debut. In their critiques of our article, Brown (2011) and Collins, Martino, and Elliott (2011) both questioned some of the decisions we made with…

  7. Reciprocal Relations between Perceived Parental Knowledge and Adolescent Substance Use and Delinquency: The Moderating Role of Parent-Teen Relationship Quality

    ERIC Educational Resources Information Center

    Abar, Caitlin C.; Jackson, Kristina M.; Wood, Mark

    2014-01-01

    The current study prospectively examined hypothesized short- and long-term reciprocal relations between perceived parental knowledge and adolescent heavy episodic drinking, marijuana use, and delinquency. Using the contextual model of parenting style (Darling & Steinberg, 1993), we examined the extent to which the bidirectional nature of…

  8. A thioesterase from an iterative fungal polyketide synthase shows macrocylization and cross-coupling activity, and may play a role in controlling iterative cycling through product off loading†

    PubMed Central

    Wang, Meng; Zhou, Hui; Wirz, Monica; Tang, Yi; Boddy, Christopher N.

    2009-01-01

    Zearalenone, a fungal macrocyclic polyketide, is a member of the resorcylic acid lactone family. Herein, we characterize in vitro the thioesterase from PKS13 in zearalenone biosynthesis (Zea TE). The excised Zea TE catalyzes macrocyclization of a linear thioester activated model of zearalenone. Zea TE also catalyzes the cross coupling of a benzoyl thioester with alcohols and amines. Kinetic characterization of the cross coupling is consistent with a ping-pong bi-bi mechanism, confirming an acyl-enzyme intermediate. Finally, the substrate specificity of the Zea TE indicates the TE may help control iterative cycling on PKS13 by rapidly off loading the final resorcylate containing product. PMID:19530704

  9. Inertial fusion features in degenerate plasmas

    NASA Astrophysics Data System (ADS)

    León, Pablo T.; Eliezer, Shalom; Piera, Mireia; Martínez-Val, José M.

    2005-04-01

    Very high plasma densities can be obtained at the end of the implosion phase in inertial fusion targets, particularly in the so-called fast-ignition scheme (Tabak et al., 1994; Mulser & Bauer, 2004), where a central hot spark is not needed at all. By properly tailoring the fuel compression stage, degenerate states can be reached (Azechi et al., 1991; Nakai et al., 1991; McCory, 1998). In that case, most of the relevant energy transfer mechanisms involving electrons are affected (Honrubia & Tikhonchuk, 2004; Bibi & Matte, 2004; Bibi et al., 2004). For instance, bremsstrahlung emission is highly suppressed (Eliezer et al., 2003). In fact, a low ignition-temperature regime appears at very high plasma densities, due to radiation leakage reduction (León et al., 2001). Stopping power and ion-electron coulomb collisions are also changed in this case, which are important mechanisms to trigger ignition by the incoming fast jet, and to launch the fusion wave from the igniting region into the colder, degenerate plasma. All these points are reviewed in this paper. Although degenerate states would not be easy to obtain by target implosion, they present a very interesting upper limit that deserves more attention in order to complete the understanding on the different domains for inertial confinement fusion.

  10. Configuration dependence of band-gap narrowing and localization in dilute GaAs1 -xBix alloys

    NASA Astrophysics Data System (ADS)

    Bannow, Lars C.; Rubel, Oleg; Badescu, Stefan C.; Rosenow, Phil; Hader, Jörg; Moloney, Jerome V.; Tonner, Ralf; Koch, Stephan W.

    2016-05-01

    Anion substitution with bismuth (Bi) in III-V semiconductors is an effective method for experimental engineering of the band gap Eg at low Bi concentrations (≤2 % ), in particular in gallium arsenide (GaAs). The inverse Bi-concentration dependence of Eg has been found to be linear at low concentrations x and dominated by a valence band defect level anticrossing between As and Bi occupied p levels. Predictive models for the valence band hybridization require a first-principle understanding which can be obtained by density functional theory with the main challenges being the proper description of Eg and the spin-orbit coupling. By using an efficient method to include these effects, it is shown here that at high concentrations Eg is modified mainly by a Bi-Bi p orbital interaction and by the large Bi atom-induced strain. In particular, we find that at high concentrations, the Bi-Bi interactions depend strongly on model periodic cluster configurations, which are not captured by tight-binding models. Averaging over various configurations supports the defect level broadening picture. This points to the role of different atomic configurations obtained by varying the experimental growth conditions in engineering arsenide band gaps, in particular for telecommunication laser technology.

  11. Effects of urbanization on benthic macroinvertebrate assemblages in contrasting environmental settings: Boston, Massachusetts; Birmingham, Alabama; and Salt Lake City, Utah

    USGS Publications Warehouse

    Cuffney, T.F.; Zappia, H.; Giddings, E.M.P.; Coles, J.F.

    2005-01-01

    Responses of invertebrate assemblages along gradients of urban intensity were examined in three metropolitan areas with contrasting climates and topography (Boston, Massachusetts; Birmingham, Alabama; Salt Lake City, Utah). Urban gradients were defined using an urban intensity index (UII) derived from basin-scale population, infrastructure, land-use, land-cover, and socioeconomic characteristics. Responses based on assemblage metrics, indices of biotic integrity (B-IBI), and ordinations were readily detected in all three urban areas and many responses could be accurately predicted simply using regional UIIs. Responses to UII were linear and did not indicate any initial resistance to urbanization. Richness metrics were better indicators of urbanization than were density metrics. Metrics that were good indicators were specific to each study except for a richness-based tolerance metric (TOLr) and one B-IBI. Tolerances to urbanization were derived for 205 taxa. These tolerances differed among studies and with published tolerance values, but provided similar characterizations of site conditions. Basin-scale land-use changes were the most important variables for explaining invertebrate responses to urbanization. Some chemical and instream physical habitat variables were important in individual studies, but not among studies. Optimizing the study design to detect basin-scale effects may have reduced the ability to detect local-scale effects. ?? 2005 by the American Fisheries Society.

  12. Streamflow, water-quality, and biological data for three tributaries to Lake Houston near Houston, Texas, 2002-04

    USGS Publications Warehouse

    East, Jeffery W.; Sneck-Fahrer, Debra A.

    2005-01-01

    -insect taxa (17) were collected at site on Caney Creek near New Caney. The benthic-macroinvertebrate index of biotic integrity (B-IBI) scores (averages of samples) for the three upstream Lake Creek sites indicate intermediate aquatic life use, and the B-IBI score for the most downstream site indicates high aquatic life use. B-IBI scores for the Peach Creek sites, in downstream order, are exceptional and high; and scores for the Caney Creek sites, in downstream order, are high and intermediate.

  13. Kernel weights optimization for error diffusion halftoning method

    NASA Astrophysics Data System (ADS)

    Fedoseev, Victor

    2015-02-01

    This paper describes a study to find the best error diffusion kernel for digital halftoning under various restrictions on the number of non-zero kernel coefficients and their set of values. As an objective measure of quality, WSNR was used. The problem of multidimensional optimization was solved numerically using several well-known algorithms: Nelder- Mead, BFGS, and others. The study found a kernel function that provides a quality gain of about 5% in comparison with the best of the commonly used kernel introduced by Floyd and Steinberg. Other kernels obtained allow to significantly reduce the computational complexity of the halftoning process without reducing its quality.

  14. From the Proton Synchroton to the Large Hadron Collider - 50 Years of Nobel Memories in High-Energy Physics

    SciTech Connect

    2009-12-07

    The seminars will be held in the Main Auditorium with transmission to : Council Chamber, IT Auditorium, Prévessin BE Auditorium , Kjell Johnssen Auditorium in Building 30, Room 40-S2-A01, and via webcast. Confirmed Speakers include: Prof. Jack Steinberger, Dr. Guenther Plass, Prof. Emilio Picasso, Dr. Steve Myers, Prof. Carlo Rubbia, Prof. Burton Richter, Dr. Lyndon Evans, Prof. Rolf-Dieter Heuer, Prof. Leon Lederman, Prof. Jim Cronin, Prof. Sheldon Glashow, Prof. Jerome Friedman, Prof. Frank Wilczek, Prof. Martinus Veltman, Prof. Gerardus 't Hooft, Prof. David Gross, Prof. Samuel Ting, Prof. Steven Weinberg (via teleconference) --- Contact: Directorate.Office@cern.ch

  15. Coinvariant algebras and fake degrees for spin Weyl groups of classical type

    NASA Astrophysics Data System (ADS)

    Baltera, Constance; Wang, Weiqiang

    2014-01-01

    The coinvariant algebra of a Weyl group plays a fundamental role in several areas of mathematics. The fake degrees are the graded multiplicities of the irreducible modules of a Weyl group in its coinvariant algebra, and they were computed by Steinberg, Lusztig and Beynon-Lusztig. In this paper we formulate a notion of spin coinvariant algebra for every Weyl group. Then we compute all the spin fake degrees for each classical Weyl group, which are by definition the graded multiplicities of the simple modules of a spin Weyl group in the spin coinvariant algebra. The spin fake degrees for the exceptional Weyl groups are given in a sequel.

  16. Sensitivity analysis of seismic hazard for Western Liguria (North Western Italy): A first attempt towards the understanding and quantification of hazard uncertainty

    NASA Astrophysics Data System (ADS)

    Barani, Simone; Spallarossa, Daniele; Bazzurro, Paolo; Eva, Claudio

    2007-05-01

    The use of logic trees in probabilistic seismic hazard analyses often involves a large number of branches that reflect the uncertainty in the selection of different models and in the selection of the parameter values of each model. The sensitivity analysis, as proposed by Rabinowitz and Steinberg [Rabinowitz, N., Steinberg, D.M., 1991. Seismic hazard sensitivity analysis: a multi-parameter approach. Bull. Seismol. Soc. Am. 81, 796-817], is an efficient tool that allows the construction of logic trees focusing attention on the parameters that have greater impact on the hazard. In this paper the sensitivity analysis is performed in order to identify the parameters that have the largest influence on the Western Liguria (North Western Italy) seismic hazard. The analysis is conducted for six strategic sites following the multi-parameter approach developed by Rabinowitz and Steinberg [Rabinowitz, N., Steinberg, D.M., 1991. Seismic hazard sensitivity analysis: a multi-parameter approach. Bull. Seismol. Soc. Am. 81, 796-817] and accounts for both mean hazard values and hazard values corresponding to different percentiles (e.g., 16%-ile and 84%-ile). The results are assessed in terms of the expected PGA with a 10% probability of exceedance in 50 years for rock conditions and account for both the contribution from specific source zones using the Cornell approach [Cornell, C.A., 1968. Engineering seismic risk analysis. Bull. Seismol. Soc. Am. 58, 1583-1606] and the spatially smoothed seismicity [Frankel, A., 1995. Mapping seismic hazard in the Central and Eastern United States. Seismol. Res. Lett. 66, 8-21]. The influence of different procedures for calculating seismic hazard, seismic catalogues (epicentral parameters), source zone models, frequency-magnitude parameters, maximum earthquake magnitude values and attenuation relationships is considered. As a result, the sensitivity analysis allows us to identify the parameters with higher influence on the hazard. Only these

  17. From the Proton Synchroton to the Large Hadron Collider - 50 Years of Nobel Memories in High-Energy Physics

    ScienceCinema

    None

    2011-10-06

    The seminars will be held in the Main Auditorium with transmission to : Council Chamber, IT Auditorium, Prévessin BE Auditorium , Kjell Johnssen Auditorium in Building 30, Room 40-S2-A01, and via webcast. Confirmed Speakers include: Prof. Jack Steinberger, Dr. Guenther Plass, Prof. Emilio Picasso, Dr. Steve Myers, Prof. Carlo Rubbia, Prof. Burton Richter, Dr. Lyndon Evans, Prof. Rolf-Dieter Heuer, Prof. Leon Lederman, Prof. Jim Cronin, Prof. Sheldon Glashow, Prof. Jerome Friedman, Prof. Frank Wilczek, Prof. Martinus Veltman, Prof. Gerardus 't Hooft, Prof. David Gross, Prof. Samuel Ting, Prof. Steven Weinberg (via teleconference) --- Contact: Directorate.Office@cern.ch

  18. COMMITTEES: SQM2004 Organising and International Advisory Committees

    NASA Astrophysics Data System (ADS)

    2005-06-01

    Organising Committee Jean Cleymans (Chairman) Zeblon Vilakazi Roger Fearick Peter Steinberg Rory Adams Bruce Becker Sarah Blyth Gareth de Vaux Heather Gray Mark Horner Nawahl Razak Artur Szostak Spencer Wheaton International Advisory Committee Federico Antinori Tim Hallman John Harris Tetsuo Hatsuda Ulrich Heinz Huan Z Huang Sonja Kabana Volker Koch Rob Lacey Jes Madsen Yasuo Miake Maurizio Morando Berndt Mueller Grazyna Odyniec Helmut Oeschler Apostolos Panagiotou Josef Pochodzalla Johann Rafelski Karel Safarik Jack Sandweiss Jürgen Schaffner-Bielich Georges Stephans Horst Stoecker Herbert Stroebele Thomas Ullrich Orlando Villalobos-Baillie Bill Zajc Joseph Zimanyi

  19. Honors

    NASA Astrophysics Data System (ADS)

    2012-02-01

    James Yoder, vice president for academic programs and dean at the Woods Hole Oceanographic Institution, Woods Hole, Mass., has been selected as a fellow of the Oceanography Society (TOS) “for his innovative and visionary application of satellite ocean color technologies to interdisciplinary oceanography and his extraordinary service to oceanography.” TOS also has three new councilors. Blanche Meeson of NASA Goddard Space Flight Center, Greenbelt, Md., is TOS's education councilor; Janet Sprintall, Scripps Institution of Oceanography, La Jolla, Calif., is TOS's councilor for physical biology; and Deborah Steinberg, Virginia Institute of Marine Sciences, Gloucester Point, is biological oceanography councilor.

  20. Production of biodiesel via enzymatic ethanolysis of the sunflower and soybean oils: modeling.

    PubMed

    Pessoa, Fernando L P; Magalhães, Shayane P; Falcão, Pedro Wagner de Carvalho

    2010-05-01

    Biodiesel has become attractive due to its environmental benefits compared with conventional diesel. Although the enzymatic synthesis of biodiesel requires low thermal energy, low conversions of enzymatic transesterification with ethanol (ethanolysis) of oils to produce biodiesel are reported as a result of deactivation of the enzyme depending on the reaction conditions. The synthesis of biodiesel via enzymatic ethanolysis of sunflower and soybean oils was investigated. Kinetic parameters for the overall reactions were fitted to experimental data available in the literature with the Ping Pong Bi-Bi mechanism including the inhibition effect of the ethanol on the activity of lipase Novozyme 435. The model was applied to a batch reactor and the experimental conversions were successfully reproduced. The modeling of a semibatch reactor with continuous addition of ethanol was also performed and the results showed a reduction of roughly 3 h in the reaction time in comparison with the batch-wise operation. PMID:20033350

  1. Functional network in posttranslational modifications: Glyco-Net in Glycoconjugate Data Bank.

    PubMed

    Miura, Nobuaki; Okada, Takuya; Murayama, Daisuke; Hirose, Kazuko; Sato, Taku; Hashimoto, Ryo; Fukushima, Nobuhiro

    2015-01-01

    Elucidating pathways related to posttranslational modifications (PTMs) such as glycosylation is of growing importance in post-genome science and technology. Graphical networks describing the relationships among glycan-related molecules, including genes, proteins, lipids, and various biological events, are considered extremely valuable and convenient tools for the systematic investigation of PTMs. Glyco-Net (http://bibi.sci.hokudai.ac.jp/functions/) can dynamically make network figures among various biological molecules and biological events. A certain molecule or event is expressed with a node, and the relationship between the molecule and the event is indicated by arrows in the network figures. In this chapter, we mention the features and current status of the Glyco-Net and a simple example of the search with the Glyco-Net. PMID:25753709

  2. Cross-Species Application of SNP Chips is Not Suitable for Identifying Runs of Homozygosity.

    PubMed

    Shafer, Aaron B A; Miller, Joshua M; Kardos, Marty

    2016-03-01

    Cross-species application of single-nucleotide polymorphism (SNP) chips is a valid, relatively cost-effective alternative to the high-throughput sequencing methods generally required to obtain a genome-wide sampling of polymorphisms. Kharzinova et al. (2015) examined the applicability of SNP chips developed in domestic bovids (cattle and sheep) to a semi-wild cervid (reindeer). The ancestors of bovids and cervids diverged between 20 and 30 million years ago (Hassanin and Douzery 2003; Bibi et al. 2013). Empirical work has shown that for a SNP chip developed in a bovid and applied to a cervid species, approximately 50% genotype success with 1% of the loci being polymorphic is expected (Miller et al. 2012). The genotyping of Kharzinova et al. (2015) follows this pattern; however, these data are not appropriate for identifying runs of homozygosity (ROH) and can be problematic for estimating linkage disequilibrium (LD) and we caution readers in this regard. PMID:26774056

  3. Aberration-Corrected Scanning Transmission Electron Microscope (STEM) Through-Focus Imaging for Three-Dimensional Atomic Analysis of Bismuth Segregation on Copper [001]/33° Twist Bicrystal Grain Boundaries.

    PubMed

    Wade, Charles Austin; McLean, Mark J; Vinci, Richard P; Watanabe, Masashi

    2016-06-01

    Scanning transmission electron microscope (STEM) through-focus imaging (TFI) has been used to determine the three-dimensional atomic structure of Bi segregation-induced brittle Cu grain boundaries (GBs). With TFI, it is possible to observe single Bi atom distributions along Cu [001] twist GBs using an aberration-corrected STEM operating at 200 kV. The depth resolution is ~5 nm. Specimens with GBs intentionally inclined with respect to the microscope's optic axis were used to investigate Bi segregant atom distributions along and through the Cu GB. It was found that Bi atoms exist at most once per Cu unit cell along the GB, meaning that no continuous GB film is present. Therefore, the reduced fracture toughness of this particular Bi-doped Cu boundary would not be caused by fracture of Bi-Bi bonds. PMID:27145975

  4. Efficient Charge Separation between Bi and Bi2 MoO6 for Photoelectrochemical Properties.

    PubMed

    Ma, Ying; Jia, Yulong; Wang, Lina; Yang, Min; Bi, Yingpu; Qi, Yanxing

    2016-04-18

    Herein, porous Bi/Bi2 MoO6 nanoparticles have been prepared by a facile in-situ reduction approach. Moreover, the morphology and Bi content of product could be controlled by varying the reaction time. By controlled fabrication, the desired porous Bi2 MoO6 nanostructure with incorporation of Bi was obtained and exhibited high photoelectric and photocatalytic activity. In particular, the samples yield a photocurrent density of 320 μA cm(-2) , which is 3.2 times that of the pure Bi2 MoO6 nanosheet (100 μA cm(-2) ) under the same conditions. UV/Vis diffuse reflectance spectroscopy analysis confirmed the surface plasmon resonance in the as-prepared porous nanoparticles. The improved photoelectric properties could be the synergistic effect of the porous structure with large surface area and effective electron-hole separations between Bi and Bi2 MoO6 . PMID:26868192

  5. Kinetic and thermodynamic investigation of enzymatic L-ascorbyl acetate synthesis.

    PubMed

    Zhang, Dong-Hao; Li, Chao; Zhi, Gao-Ying

    2013-12-01

    Kinetics and thermodynamics of lipase-catalyzed esterification of l-ascorbic acid in acetone were investigated by using vinyl acetate as acyl donor. The results showed that l-ascorbic acid could generate inhibition effect on lipase activity. A suitable model, Ping-Pong Bi-Bi mechanism having substrate inhibition, was thus introduced to describe the enzymatic kinetics. Furthermore, the kinetic and thermodynamic parameters were calculated from a series of experimental data according to the kinetic model. The inhibition constant of L-ascorbic acid was also obtained, which seemed to imply that enhancing reaction temperature could depress the substrate inhibition. Besides, the activation energy values of the first-step and the second-step reaction were estimated to be 37.31 and 4.94 kJ/mol, respectively, demonstrating that the first-step reaction was the rate-limiting reaction and could be easily improved by enhancing temperature. PMID:24211407

  6. Zinc Oxide Nanoparticles Supported Lipase Immobilization for Biotransformation in Organic Solvents: A Facile Synthesis of Geranyl Acetate, Effect of Operative Variables and Kinetic Study.

    PubMed

    Patel, Vrutika; Shah, Chandani; Deshpande, Milind; Madamwar, Datta

    2016-04-01

    The present study describes grafting of zinc oxide (ZnO) nanoparticles with polyethyleneimine (PEI) followed by modification with glutraldehyde used as the bridge for binding the enzyme to support. The prepared nanocomposites were then characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis, and transmission electron microscopy, utilized for synthesis of geranyl acetate in n-hexane. Among all the three prepared nanocomposites (ZnO + PEI, ZnO + PEI + SAA, ZnO + PEI + GLU), Candida rugosa lipase immobilized on ZnO-PEI-GLU was found to be best for higher ester synthesis. The operating conditions that maximized geranyl acetate resulted in the highest yield of 94 % in 6 h, molar ratio of 0.1:0.4 M (geraniol/vinyl acetate) in the presence of n-hexane as reaction medium. Various kinetic parameters such as V max, K i(G), K m(G), and K m(VA) were determined using nonlinear regression analysis for order bi-bi mechanism. The kinetic study showed that reaction followed order bi-bi mechanism with inhibition by geraniol. Activation energy (E a ) was found to be lower for immobilized lipase (12.31 kJ mol(-1)) than crude lipase (19.04 kJ mol(-1)) indicating better catalytic efficiency of immobilized lipase. Immobilized biocatalyst demonstrated 2.23-fold increased catalytic activity than crude lipase and recycled 20 times. The studies revealed in this work showed a promising perspective of using low-cost nanobiocatalysts to overcome the well-known drawbacks of the chemical-catalyzed route. PMID:26749293

  7. Antiphase Boundaries in the Turbostratically Disordered Misfit Compound (BiSe)(1+δ)NbSe2.

    PubMed

    Mitchson, Gavin; Falmbigl, Matthias; Ditto, Jeffrey; Johnson, David C

    2015-11-01

    (BiSe)(1+δ)NbSe2 ferecrystals were synthesized in order to determine whether structural modulation in BiSe layers, characterized by periodic antiphase boundaries and Bi-Bi bonding, occurs. Specular X-ray diffraction revealed the formation of the desired compound with a c-axis lattice parameter of 1.21 nm from precursors with a range of initial compositions and initial periodicities. In-plane X-ray diffraction scans could be indexed as hk0 reflections of the constituents, with a rectangular basal BiSe lattice and a trigonal basal NbSe2 lattice. Electron micrographs showed extensive turbostratic disorder in the samples and the presence of periodic antiphase boundaries (approximately 1.5 nm periodicity) in BiSe layers oriented with the [110] direction parallel to the zone axis of the microscope. This indicates that the structural modulation in the BiSe layers is not due to coherency strain resulting from commensurate in-plane lattices. Electrical transport measurements indicate that holes are the dominant charge carrying species, that there is a weak decrease in resistivity as temperature decreases, and that minimal charge transfer occurs from the BiSe to NbSe2 layers. This is consistent with the lack of charge transfer from the BiX to the TX2 layers reported in misfit layer compounds where antiphase boundaries were observed. This suggests that electronic considerations, i.e., localization of electrons in the Bi-Bi pairs at the antiphase boundaries, play a dominant role in stabilizing the structural modulation. PMID:26465820

  8. A syllabus for Jewish medical ethics in the context of general bioethics.

    PubMed

    Gesundheit, Benjamin; Shaham, Dorith

    2008-05-01

    Since the beginning of medical history, ethics has interested medical practitioners. The subject has become particularly important in recent years due to the huge advancements in medicine and medical technology and has elicited much public interest. While international ethical principles and guidelines have been established, classical Jewish tradition has always placed great emphasis on bioethics. Prof. Avraham Steinberg's monumental Encyclopedia of Jewish Medical Ethics presents the subject comprehensively and in depth. We propose a bioethics syllabus, to be integrated into the medical curriculum in three stages: i) preclinical - covering basic ethical concepts and principles, relevant history, and ethical codes; ii) clinical - covering bioethical topics relating to the human life cycle; iii) prior to students' final examinations and further specialization - covering bioethical topics relating to their personal interests. Steinberg's Encyclopedia is an ideal basis for the development of a professional course, including Jewish traditional aspects. Such a course would provide future physicians with a varied cultural and intercultural background, help shape their image, and improve the quality of medical care. PMID:18605372

  9. Metal-Metal Bonding in Uranium-Group 10 Complexes.

    PubMed

    Hlina, Johann A; Pankhurst, James R; Kaltsoyannis, Nikolas; Arnold, Polly L

    2016-03-16

    Heterobimetallic complexes containing short uranium-group 10 metal bonds have been prepared from monometallic IU(IV)(OAr(P)-κ(2)O,P)3 (2) {[Ar(P)O](-) = 2-tert-butyl-4-methyl-6-(diphenylphosphino)phenolate}. The U-M bond in IU(IV)(μ-OAr(P)-1κ(1)O,2κ(1)P)3M(0), M = Ni (3-Ni), Pd (3-Pd), and Pt (3-Pt), has been investigated by experimental and DFT computational methods. Comparisons of 3-Ni with two further U-Ni complexes XU(IV)(μ-OAr(P)-1κ(1)O,2κ(1)P)3Ni(0), X = Me3SiO (4) and F (5), was also possible via iodide substitution. All complexes were characterized by variable-temperature NMR spectroscopy, electrochemistry, and single crystal X-ray diffraction. The U-M bonds are significantly shorter than any other crystallographically characterized d-f-block bimetallic, even though the ligand flexes to allow a variable U-M separation. Excellent agreement is found between the experimental and computed structures for 3-Ni and 3-Pd. Natural population analysis and natural localized molecular orbital (NLMO) compositions indicate that U employs both 5f and 6d orbitals in covalent bonding to a significant extent. Quantum theory of atoms-in-molecules analysis reveals U-M bond critical point properties typical of metallic bonding and a larger delocalization index (bond order) for the less polar U-Ni bond than U-Pd. Electrochemical studies agree with the computational analyses and the X-ray structural data for the U-X adducts 3-Ni, 4, and 5. The data show a trend in uranium-metal bond strength that decreases from 3-Ni down to 3-Pt and suggest that exchanging the iodide for a fluoride strengthens the metal-metal bond. Despite short U-TM (transition metal) distances, four other computational approaches also suggest low U-TM bond orders, reflecting highly transition metal localized valence NLMOs. These are more so for 3-Pd than 3-Ni, consistent with slightly larger U-TM bond orders in the latter. Computational studies of the model systems (PH3)3MU(OH)3I (M = Ni, Pd) reveal

  10. The really "stealth" mantle metasomatism

    NASA Astrophysics Data System (ADS)

    Puziewicz, Jacek; Matusiak-Małek, Magdalena; Ntaflos, Theodoros; Grégoire, Michel; Kukuła, Anna; Wojtulek, Piotr

    2015-04-01

    The Lower Silesian/Upper Lusatian domain of European subcontinental lithospheric mantle is dominated by two kinds of harzburgites: A - not affected or slightly affected by silicate melt metasomatism related to migration of lavas during formation of Cenozoic Central European Volcanic Province, and B - strongly overprinted by those lavas (Puziewicz et al. 2015, IJES, DOI 10.1007/s00531-014-1134-2). The study of Matusiak-Małek et al. (2014, J Petrol 55, 1799-1828) shows that the A harzburgites untouched by metasomatic events contain no clinopyroxene. Part of the A harzburgites contains clinopyroxene which has "primary" appearance but was added to the host during metasomatic event(s) overprinting the primary mineral assemblage. The metasomatic nature of this clinopyroxene can be recognized by its major and trace element chemical composition, and the mineral is a good example of the "stealth" metasomatic phase (O'Reilly & Griffin 2013, Springer). One of the typical features of this kind of clinopyroxene are LREE enriched REE patterns. We have discovered single xenoliths containing clinopyroxene with LREE depleted patterns in Steinberg near Görlitz (Lower Silesian/Upper Lusatian Region) and in Feldstein near Suhl (Heldburger Gangschar in Thuringia). Usually these kind of REE patterns is considered to be a relic of primary mineral assemblage subjected to strong melt-depletion. However, clinopyroxene from Steinberg is texturally late phase. Its major element chemical composition suggests that it is not a residue after partial melting, but a late silicate-melt metasomatic addition to the host rock which preceded the xenolith entrainment in the erupting lava. Thus, the metasomatising melt must have had characteristics enabling the precipitation of LREE depleted clinopyroxene. The existence of such the melts is clearly shown by the clinopyroxene from websterite cumulate from Dobkovičky in Eger Rift (Ackerman et al. 2012, J Geosci 58, 199-219), which has LREE depleted

  11. Quality of Early Family Relationships and Individual Differences in the Timing of Pubertal Maturation in Girls: A Longitudinal Test of an Evolutionary Model

    PubMed Central

    Ellis, Bruce J.; McFadyen-Ketchum, Steven; Dodge, Kenneth A.; Pettit, Gregory S.; Bates, John E.

    2009-01-01

    In an 8-year prospective study of 173 girls and their families, the authors tested predictions from J. Belsky, L. Steinberg, and P. Draper's (1991) evolutionary model of individual differences in pubertal timing. This model suggests that more negative–coercive (or less positive–harmonious) family relationships in early childhood provoke earlier reproductive development in adolescence. Consistent with the model, fathers' presence in the home, more time spent by fathers in child care, greater supportiveness in the parental dyad, more father–daughter affection, and more mother–daughter affection, as assessed prior to kindergarten, each predicted later pubertal timing by daughters in 7th grade, The positive dimension of family relationships, rather than the negative dimension, accounted for these relations. In total, the quality of fathers' investment in the family emerged as the most important feature of the proximal family environment relative to daughters' pubertal timing. PMID:10474213

  12. Dynamic Strength of Tantalum under impact

    NASA Astrophysics Data System (ADS)

    Glam, Benny; Werdiger, Meir; Pistinner, Shlomi

    2013-06-01

    Plane impact experiments of double shock and shock-rarefaction in Tantalum were carried out in a gas gun. VISAR diagnostics has been implemented to measure the particle velocity and the free surface velocity. The VISAR information was utilized to study the dynamic strength of Tantalum under compression and tension. The pressure in the experiments was below 35 GPa. In this pressure range the dominant mechanism is expected to be dislocation motion. A 1-d hydrodynamic code was used in order to match various strength models. As expected, both the Johnson-Cook and the Guinan-Steinberg models do not reproduce the experimental results. Therefore in this paper we compare the Zerilli-Armstrong model which has been recently calibrated at strain rate of 6 x 103 s-1 using the split Kowalsky-Hopkinson bar to our experimental results at strain rate of 106 s-1.

  13. On the dynamic strength of 304l stainless steel under impact

    NASA Astrophysics Data System (ADS)

    Werdiger, Meir; Glam, Benny; Bakshi, Lior; Moshe, Ella; Horovitz, Yossef; Pistinner, Shlomi Levi

    2012-03-01

    Uniaxial strain plane impact (300-1700 m/s), loading and reloading experiments carried out on SS304L are reported. The aim of these experiments was to measure the material strength properties under shock compression. Most of the experiments reported here show a viscous type elastic precursor. The experimental results are compared to numerical simulations performed using a 1D code. The input physics to the simulations are the Steinberg equation of state and Johnson-Cook strength model. This model has been previously calibrated under uniaxial stress conditions in the rangee ɛ =1-5×103 s-1. Our experiments extended the data into the regione ɛ =105 -106 s-1. In spite of this extrapolation, there is a general agreement between simulations and experiments. However, differences in some details still exist.

  14. Experimental and numerical investigations of beryllium strength models using the Rayleigh-Taylor instability

    SciTech Connect

    Henry de Frahan, M. T. Johnsen, E.; Belof, J. L.; Cavallo, R. M.; Ancheta, D. S.; El-dasher, B. S.; Florando, J. N.; Gallegos, G. F.; LeBlanc, M. M.; Raevsky, V. A.; Ignatova, O. N.; Lebedev, A.

    2015-06-14

    We present a set of high explosive driven Rayleigh-Taylor strength experiments for beryllium to produce data to distinguish predictions by various strength models. Design simulations using existing strength model parameterizations from Steinberg-Lund and Preston-Tonks-Wallace (PTW) suggested an optimal design that would delineate between not just different strength models, but different parameters sets of the PTW model. Application of the models to the post-shot results, however, suggests growth consistent with little material strength. We focus mostly on efforts to simulate the data using published strength models as well as the more recent RING relaxation model developed at VNIIEF. The results of the strength experiments indicate weak influence of strength in mitigating the growth with the RING model coming closest to predicting the material behavior. Finally, we present shock and ramp-loading recovery experiments.

  15. Dynamic material properties of refractory materials: Tantalum and tantalum/tungsten alloys

    SciTech Connect

    Furnish, M.D.; Chhabildas, L.C.; Lassila, D.H.; Steinberg, D.J.

    1995-08-01

    We have made a careful set of impact wave-profile measurements (16 profiles) on tantalum and tantalum-tungsten alloys at relatively low stresses (to 15 GPa). Alloys used were Ta{sub 97.5}W{sub 2.5} and Ta{sub 90}W{sub 10} (wt. %) with oxygen contents of 30--70 ppM. Information available from these experiments includes Hugoniot, elastic limits, loading fates, spall strength, unloading paths, reshock structure and specimen thickness effects. Hugoniot and spall properties are illustrated, and are consistent with expectations from earlier work. Modeling the tests with the Steinberg-Lund rate-dependent material model provides for an excellent match of the shape of the plastic wave, although the release wave is not well modeled. There is also a discrepancy between experiments and calculations regarding the relative timing of the elastic and plastic waves that may be due to texture effects.

  16. Experimental and numerical investigations of beryllium strength models using the Rayleigh-Taylor instability

    SciTech Connect

    Henry de Frahan, M. T.; Belof, J. L.; Cavallo, R. M.; Raevsky, V. A.; Ignatova, O. N.; Lebedev, A.; Ancheta, D. S.; El-dasher, B. S.; Florando, J. N.; Gallegos, G. F.; Johnsen, E.; LeBlanc, M. M.

    2015-06-14

    A recent collaboration between LLNL and VNIIEF has produced a set of high explosive driven Rayleigh-Taylor strength data for beryllium. Design simulations using legacy strength models from Steinberg-Lund and Preston-Tonks-Wallace (PTW) suggested an optimal design that would delineate between not just different strength models, but different parameters sets of the PTW model. Application of the models to the post-shot results, however, shows close to classical growth. We characterize the material properties of the beryllium tested in the experiments. We also discuss recent efforts to simulate the data using the legacy strength models as well as the more recent RING relaxation model developed at VNIIEF. Finally, we present shock and ramp-loading recovery experiments conducted as part of the collaboration.

  17. The prejudiced personality, racism, and anti-Semitism: the PR scale forty years later.

    PubMed

    Dunbar, E

    1995-10-01

    The relationship of prejudiced personality traits with racism and anti-Semitism was examined with 150 Asian American and White university students. The Prejudice (PR) scale, composed of 32 items from the Minnesota Multiphasic Personality Inventory, was administered along with the McConahay racism scale and the Selznick and Steinberg Anti-Semitism scale. Results indicated that for Whites, the PR scale was significantly correlated with old-fashioned and modern racism and anti-Semitism, replicating Gough's 1951 study (Gough, 1951b) with the PR scale. However, no such relationship was observed for the Asian American group. This suggests that personality traits of prejudicial attitudes may be relatively stable for Whites but may not be related to outgroup bias for other racial or ethnic groups. PMID:8656327

  18. CONDENSED MATTER: STRUCTURE, MECHANICAL AND THERMAL PROPERTIES: Numerical Simulation of Wave Propagation and Phase Transition of Tin under Shock-Wave Loading

    NASA Astrophysics Data System (ADS)

    Song, Hai-Feng; Liu, Hai-Feng; Zhang, Guang-Cai; Zhao, Yan-Hong

    2009-06-01

    We undertake a numerical simulation of shock experiments on tin reported in the literature, by using a multiphase equation of state (MEOS) and a multiphase Steinberg Guinan (MSG) constitutive model for tin in the β, γ and liquid phases. In the MSG model, the Bauschinger effect is considered to better describe the unloading behavior. The phase diagram and Hugoniot of tin are calculated by MEOS, and they agree well with the experimental data. Combined with the MEOS and MSG models, hydrodynamic computer simulations are successful in reproducing the measured velocity profile of the shock wave experiment. Moreover, by analyzing the mass fraction contour as well as stress and temperature profiles of each phase for tin, we further discuss the complex behavior of tin under shock-wave loading.

  19. Experimental and numerical investigations of beryllium strength models using the Rayleigh-Taylor instability

    NASA Astrophysics Data System (ADS)

    Henry de Frahan, M. T.; Belof, J. L.; Cavallo, R. M.; Raevsky, V. A.; Ignatova, O. N.; Lebedev, A.; Ancheta, D. S.; El-dasher, B. S.; Florando, J. N.; Gallegos, G. F.; Johnsen, E.; LeBlanc, M. M.

    2015-06-01

    We present a set of high explosive driven Rayleigh-Taylor strength experiments for beryllium to produce data to distinguish predictions by various strength models. Design simulations using existing strength model parameterizations from Steinberg-Lund and Preston-Tonks-Wallace (PTW) suggested an optimal design that would delineate between not just different strength models, but different parameters sets of the PTW model. Application of the models to the post-shot results, however, suggests growth consistent with little material strength. We focus mostly on efforts to simulate the data using published strength models as well as the more recent RING relaxation model developed at VNIIEF. The results of the strength experiments indicate weak influence of strength in mitigating the growth with the RING model coming closest to predicting the material behavior. Finally, we present shock and ramp-loading recovery experiments.

  20. A review of the kinetic statistical strength model

    SciTech Connect

    Attia, A.V.

    1996-03-11

    This is a review of the Kinetic-Statistical Strength (KSS) model described in the report ``Models of Material Strength, Fracture and Failure`` by V. Kuropatenko and V. Bychenkov. The models for metals subjected to high strain rates (explosions) are focussed on. Model implementation appears possible in a hydrocode. Applying the model to the shock response of metals will require a data source for the Weibull parameter {alpha}{sub u}, short of measuing the strength of specimens of various sizes. Model validation will require more detail on the experiments successfully calculated by SPRUT. Evaluation of the KSS model is needed against other existing rate-dependent models for metals such as the Steinberg-Lund or MTS model on other shock experiments.

  1. Congressional liaison task force - a briefing of the October 1994 meeting

    SciTech Connect

    1994-12-31

    As the US Senate overturned roadblocks attempting-unsuccessfully-to halt passage of the elementary and secondary education reauthorization legislation representatives from several federal agencies and laboratories addressed Congressional Liaison Task Force (CLTF) participants October 12th. They spoke about their commitment, programs, and accomplishments toward the nation`s science knowledge, particularly at the precollege level. Marjorie S. Steinberg legislative assistant to bill cosponsor Sen. Jeff Bingaman (DNM), and Gary Allen, Triangle Coalition director of Governmental affairs, spoke about education legislation and specifically about the Technology for Education Act that was on the Senate floor for a vote in October and now is law. Bruce A. Fuchs talked about the National Institute of Health`s (NIH) work in science literacy and education. The National Aeronautics and Space Administration`s (NASA) Frank C. Owens and Eddie Anderson contributed to this report.

  2. INFLUENCE OF DYNAMIC PROPERTIES ON PERTURBATION GROWTH IN TANTALUM

    SciTech Connect

    Igonin, V. V.; Ignatova, O. N.; Lebedev, A. I.; Lebedeva, M. O.; Nadezhin, S. S.; Podurets, A. M.; Raevsky, V. A.; Solovyev, V. P.; Zocher, M. A.; Preston, D. L.

    2009-12-28

    The perturbation method is employed in an experimental-numerical study of the behavior of Ta subjected to both shock and shockless (approximately quasi-isentropic) loading. The loading produces large deformation plastic flow, pressures on the order of 10-80 GPa, and strain rates on the order of 10{sup 5}-10{sup 9} s{sup -1}. Metallographic analysis is used to assess microstructural changes. Perturbation growth is reasonably well predicted with the use of a finite element continuum code and the Steinberg-Glushak model. Perturbation growth in Ta is compared to that of Al and Cu. Observations are made concerning fundamental differences in the behavior of fcc versus bcc materials subjected to the studied load environment. Ramifications of these differences on model development is discussed.

  3. MESOSCALE SIMULATIONS OF POWDER COMPACTION

    SciTech Connect

    Lomov, Ilya; Fujino, Don; Antoun, Tarabay; Liu, Benjamin

    2009-12-28

    Mesoscale 3D simulations of shock compaction of metal and ceramic powders have been performed with an Eulerian hydrocode GEODYN. The approach was validated by simulating a well-characterized shock compaction experiment of a porous ductile metal. Simulation results using the Steinberg material model and handbook values for solid 2024 aluminum showed good agreement with experimental compaction curves and wave profiles. Brittle ceramic materials are not as well studied as metals, so a simple material model for solid ceramic (tungsten carbide) has been calibrated to match experimental compaction curves. Direct simulations of gas gun experiments with ceramic powders have been performed and showed good agreement with experimental data. The numerical shock wave profile has same character and thickness as that measured experimentally using VISAR. The numerical results show reshock states above the single-shock Hugoniot line as observed in experiments. We found that for good quantitative agreement with experiments 3D simulations are essential.

  4. Mesoscale Simulations of Powder Compaction

    NASA Astrophysics Data System (ADS)

    Lomov, Ilya.; Fujino, Don; Antoun, Tarabay; Liu, Benjamin

    2009-12-01

    Mesoscale 3D simulations of shock compaction of metal and ceramic powders have been performed with an Eulerian hydrocode GEODYN. The approach was validated by simulating a well-characterized shock compaction experiment of a porous ductile metal. Simulation results using the Steinberg material model and handbook values for solid 2024 aluminum showed good agreement with experimental compaction curves and wave profiles. Brittle ceramic materials are not as well studied as metals, so a simple material model for solid ceramic (tungsten carbide) has been calibrated to match experimental compaction curves. Direct simulations of gas gun experiments with ceramic powders have been performed and showed good agreement with experimental data. The numerical shock wave profile has same character and thickness as that measured experimentally using VISAR. The numerical results show reshock states above the single-shock Hugoniot line as observed in experiments. We found that for good quantitative agreement with experiments 3D simulations are essential.

  5. Aluminum Rayleigh Taylor Strength Measurements and Calculations

    SciTech Connect

    Lindquist, M J; Cavallo, R M; Lorenz, K T; Pollaine, S M; Remington, B A; Raevsky, V A

    2007-01-10

    A traditional approach to the study of material strength has been revitalized at the Russian Federal Nuclear Center (VNIIEF). Rayleigh Taylor strength experiments have long been utilized to measure the material response of metals at high pressure and strain rates. A modulated (sinusoidal or sawtooth perturbation) surface is shocklessly (quasi-isentropically) accelerated by a high explosive (HE) driver, and radiography is used to measure the perturbation amplitude as a function of time. The Aluminum T-6061 targets are designed with several sets of two-dimensional sawtooth perturbations machined on the loading surface. The HE driver was designed to reach peak pressures in the range of 200 to 300 kbar and strain rates in the range of 10{sup 4} - 10{sup 6} s{sup -1}. The standard constitutive strength models, Steinberg-Guinan (SG) [1], Steinberg-Lund (SL) [2], Preston-Tonks-Wallace (PTW) [3], Johnson-Cooke (JC) [4], and Mechanical Threshold Stress (MTS) [5], have been calibrated by traditional techniques: (Hopkinson-Bar, Taylor impact, flyer plate/shock-driven experiments). The VNIIEF experimental series accesses a strain rate regime not attainable using traditional methods. We have performed a detailed numerical study with a two-dimensional Arbitrary Lagrangian Eulerian hydrodynamics computer code containing several constitutive strength models to predict the perturbation growth. Results show that the capabilities of the computational methodology predict the amplitude growth to within 5 percent of the measured data, thus validating both the code and the strength models under the given conditions and setting the stage for credible future design work using different materials.

  6. Bidirectional associations between bedtime parenting and infant sleep: Parenting quality, parenting practices, and their interaction.

    PubMed

    Philbrook, Lauren E; Teti, Douglas M

    2016-06-01

    In keeping with transactional conceptualizations of infant sleep development (Sadeh, Tikotzky, & Scher, 2010), the present study was an examination of longitudinal, bidirectional linkages between bedtime parenting (through direct observations of parenting practices and quality) and infant sleep across the first 6 months postpartum. In doing so, we also drew from Darling and Steinberg's (1993) conceptual model to examine parenting quality as a moderator of linkages between specific bedtime practices and infant sleep. Multilevel model analyses revealed that the strongest increases in infant nighttime sleep across the first 6 months occurred among infants of mothers who engaged in low levels of nursing at bedtime. Within-person linkages between mothers' emotional availability (EA) at bedtime, infant distress, and infant sleep were found, such that at time points when mothers were more emotionally available, infants were less distressed and slept more throughout the night. Several moderating effects of maternal EA on linkages between parenting practices and infant sleep were obtained that were consistent with predictions from Darling and Steinberg (1993). Higher maternal EA in combination with less close contact at bedtime was associated with more infant sleep across the night on average, and higher EA in combination with fewer arousing bedtime activities predicted more rapid increases in infant sleep with age. Finally, there was evidence of infant-driven effects, as higher infant nighttime distress predicted lower EA at subsequent time points. Results showcased the complex, reciprocal interplay between parents and infants in the development of infant sleep patterns and parenting behavior during the first 6 months postpartum. (PsycINFO Database Record PMID:27010601

  7. Probes of hydrogen tunneling with horse liver alcohol dehydrogenase at subzero temperatures.

    PubMed

    Tsai, S; Klinman, J P

    2001-02-20

    The temperature dependence of steady-state kinetics has been studied with horse liver alcohol dehydrogenase (HLADH) using protonated and deuterated benzyl alcohol as substrates in methanol/water mixtures between +3 and -50 degrees C. Additionally, the competitive isotope effects, k(H)/k(T) and k(D)/k(T), were measured. The studies indicate increasing kinetic complexity for wild-type HLADH at subzero temperatures. Consistent with earlier findings at 25 degrees C [Bahnson et al. (1993) Biochemistry 31, 5503], the F93W mutant shows much less kinetic complexity than the wild-type enzyme between 3 and -35 degrees C. An analysis of noncompetitive deuterium isotope effects and competitive tritium isotope effects leads to the conclusion that the reaction of F93W involves substantial hydrogen tunneling down to -35 degrees C. The effect of methanol on kinetic properties for the F93W mutant was analyzed, showing a dependence of competitive KIEs on the NAD(+) concentration. This indicates a more random bi--bi kinetic mechanism, in comparison to an ordered bi-bi kinetic mechanism in water. Although MeOH also affects the magnitude of the reaction rates and, to some extent, the observed KIEs, the ratio of ln k(H)/k(T) to ln k(D)/k(T) for primary isotope effects has not changed in methanol, and we conclude little or no change in kinetic complexity. Importantly, the degree of tunneling, as shown from the relationship between the secondary k(H)/k(T) and k(D)/k(T) values, is the same in water and MeOH/water mixtures, implicating similar trajectories for H transfer in both solvents. In a recent study of a thermophilic alcohol dehydrogenase [Kohen et al. (1999) Nature 399, 496], it was shown that decreases in temperatures below a transition temperature lead to decreased tunneling. This arises because of a change in protein dynamics below a break point in enzyme activity [Kohen et al. (2000) J. Am. Chem. Soc. 122, 10738-10739]. For the mesophilic HLADH described herein, an opposite

  8. Linking Hydrologic Alteration to Biological Impairment in Urbanizing Streams of the Puget Lowland, Washington, USA1

    PubMed Central

    DeGasperi, Curtis L; Berge, Hans B; Whiting, Kelly R; Burkey, Jeff J; Cassin, Jan L; Fuerstenberg, Robert R

    2009-01-01

    We used a retrospective approach to identify hydrologic metrics with the greatest potential for ecological relevance for use as resource management tools (i.e., hydrologic indicators) in rapidly urbanizing basins of the Puget Lowland. We proposed four criteria for identifying useful hydrologic indicators: (1) sensitive to urbanization consistent with expected hydrologic response, (2) demonstrate statistically significant trends in urbanizing basins (and not in undeveloped basins), (3) be correlated with measures of biological response to urbanization, and (4) be relatively insensitive to potentially confounding variables like basin area. Data utilized in the analysis included gauged flow and benthic macroinvertebrate data collected at 16 locations in 11 King County stream basins. Fifteen hydrologic metrics were calculated from daily average flow data and the Pacific Northwest Benthic Index of Biological Integrity (B-IBI) was used to represent the gradient of response of stream macroinvertebrates to urbanization. Urbanization was represented by percent Total Impervious Area (%TIA) and percent urban land cover (%Urban). We found eight hydrologic metrics that were significantly correlated with B-IBI scores (Low Pulse Count and Duration; High Pulse Count, Duration, and Range; Flow Reversals, TQmean, and R-B Index). Although there appeared to be a great deal of redundancy among these metrics with respect to their response to urbanization, only two of the metrics tested – High Pulse Count and High Pulse Range – best met all four criteria we established for selecting hydrologic indicators. The increase in these high pulse metrics with respect to urbanization is the result of an increase in winter high pulses and the occurrence of high pulse events during summer (increasing the frequency and range of high pulses), when practically none would have occurred prior to development. We performed an initial evaluation of the usefulness of our hydrologic indicators by

  9. Structural characterization of Bi{sub 2}Te{sub 3} and Sb{sub 2}Te{sub 3} as a function of temperature using neutron powder diffraction and extended X-ray absorption fine structure techniques

    SciTech Connect

    Mansour, A. N.; Wong-Ng, W.; Huang, Q.; Tang, W.; Thompson, A.; Sharp, J.

    2014-08-28

    The structure of Bi{sub 2}Te{sub 3} (Seebeck coefficient Standard Reference Material (SRM™ 3451)) and the related phase Sb{sub 2}Te{sub 3} have been characterized as a function of temperature using the neutron powder diffraction (NPD) and the extended X-ray absorption fine structure (EXAFS) techniques. The neutron structural studies were carried out from 20 K to 300 K for Bi{sub 2}Te{sub 3} and from 10 K to 298 K for Sb{sub 2}Te{sub 3}. The EXAFS technique for studying the local structure of the two compounds was conducted from 19 K to 298 K. Bi{sub 2}Te{sub 3} and Sb{sub 2}Te{sub 3} are isostructural, with a space group of R3{sup ¯}m. The structure consists of repeated quintuple layers of atoms, Te2-M-Te1-M-Te2 (where M = Bi or Sb) stacking along the c-axis of the unit cell. EXAFS was used to examine the bond distances and static and thermal disorders for the first three shells of Bi{sub 2}Te{sub 3} and Sb{sub 2}Te{sub 3} as a function of temperature. The temperature dependencies of thermal disorders were analyzed using the Debye and Einstein models for lattice vibrations. The Debye and Einstein temperatures for the first two shells of Bi{sub 2}Te{sub 3} are similar to those of Sb{sub 2}Te{sub 3} within the uncertainty in the data. However, the Debye and Einstein temperatures for the third shell of Bi-Bi are significantly lower than those of the third shell of Sb-Sb. The Einstein temperature for the third shell is consistent with a soft phonon mode in both Bi{sub 2}Te{sub 3} and Sb{sub 2}Te{sub 3}. The lower Einstein temperature of Bi-Bi relative to Sb-Sb is consistent with the lower value of thermal conductivity of Bi{sub 2}Te{sub 3} relative to Sb{sub 2}Te{sub 3}.

  10. Kinetic modeling and docking study of immobilized lipase catalyzed synthesis of furfuryl acetate.

    PubMed

    Mathpati, Ashwini C; Badgujar, Kirtikumar C; Bhanage, Bhalchandra M

    2016-03-01

    The present work deals with the kinetic modeling and docking study for the furfuryl acetate synthesis using immobilized Burkholderia cepacia (BCL) lipase. Initially various lipases were immobilized on hydroxypropyl methyl cellulose (HPMC) and poly vinyl alcohol (PVA) base hybrid polymer matrix. After screening of various immobilized biocatalysts, HPMC:PVA:BCL was found to be a robust biocatalyst. Various reaction conditions were optimized using response surface methodology (RSM) based on a four-factor-three-level Box-Behnken design. The optimal conditions were obtained at molar ratio of 1:2 of furfuryl alcohol to acyl donor, temperature 50°C with catalyst loading of 30mg in 3mL of non-aqueous media toluene. Under these conditions 99.98% yield was obtained in 3h. The Arrhenius plot showed that the activation energy for furfuryl acetate synthesis was 10.68kcal/mol. The kinetics of reaction was studied close to optimized conditions which obey order bi-bi model. Molecular docking study was carried out to understand the active site of BCL which is responsible for the reaction. It was observed that the reaction proceeds via acylation of the active serine of BCL and demonstrating strong hydrogen bond between the substrate and histidine site. The catalyst recyclability study was carried up to five cycles. PMID:26827768

  11. Mechanistic Study of Manganese-Substituted Glycerol Dehydrogenase Using a Kinetic and Thermodynamic Analysis

    PubMed Central

    Fang, Baishan; Niu, Jin; Ren, Hong; Guo, Yingxia; Wang, Shizhen

    2014-01-01

    Mechanistic insights regarding the activity enhancement of dehydrogenase by metal ion substitution were investigated by a simple method using a kinetic and thermodynamic analysis. By profiling the binding energy of both the substrate and product, the metal ion's role in catalysis enhancement was revealed. Glycerol dehydrogenase (GDH) from Klebsiella pneumoniae sp., which demonstrated an improvement in activity by the substitution of a zinc ion with a manganese ion, was used as a model for the mechanistic study of metal ion substitution. A kinetic model based on an ordered Bi-Bi mechanism was proposed considering the noncompetitive product inhibition of dihydroxyacetone (DHA) and the competitive product inhibition of NADH. By obtaining preliminary kinetic parameters of substrate and product inhibition, the number of estimated parameters was reduced from 10 to 4 for a nonlinear regression-based kinetic parameter estimation. The simulated values of time-concentration curves fit the experimental values well, with an average relative error of 11.5% and 12.7% for Mn-GDH and GDH, respectively. A comparison of the binding energy of enzyme ternary complex for Mn-GDH and GDH derived from kinetic parameters indicated that metal ion substitution accelerated the release of dioxyacetone. The metal ion's role in catalysis enhancement was explicated. PMID:24896258

  12. Enzymatic Synthesis of Furfuryl Alcohol Ester with Oleic Acid by Candida antarctica Lipase B and Its Kinetic Study

    NASA Astrophysics Data System (ADS)

    Sengupta, Avery; Dey, Tanmoy; Ghosh, Mahua; Ghosh, Jaydip; Ghosh, Santinath

    2012-08-01

    This study investigated the successful enzymatic production of furfuryl oleate and its detailed kinetic study by Michaelis-Menten model. Esterification of oleic acid and furfuryl alcohol by Candida antarctica lipase B (Novozym 435 preparation) in a solvent free system was studied in the present work at 1:1 molar ratio of furfuryl alcohol and oleic acid. About 99 % conversion (on the basis of oleic acid) has been achieved within 6 h at 5 % enzyme concentration. Ping-pong bi-bi mechanism (inhibition phenomenon taken into account) was applied to describe the ratios as a complex kinetic model. The kinetic parameters were determined using MATLAB language programme. The two initial rate constants KA and KB respectively were found out by different progress curves plotted with the help of MATLAB language programme. It was concluded from the results that furfuryl alcohol considerably inhibited the enzymatic reaction while oleic acid had negligible inhibitory effect. It was clearly seen that the initial rate was increased with the increase in the furfuryl alcohol concentration until 2 M/L after which there was a drop in the initial rate depicting the inhibitory effect of furfuryl alcohol. Surprisingly, it has been observed that addition of 0.1 mol of product activated the esterification reaction. Finally, the model was found to be statistically fitting well with the experimental data.

  13. An asymmetric supercapacitor with highly dispersed nano-Bi2O3 and active carbon electrodes

    NASA Astrophysics Data System (ADS)

    Qu, Deyu; Wang, Lili; Zheng, Dong; Xiao, Liang; Deng, Bohua; Qu, Deyang

    2014-12-01

    An asymmetric supercapacitor constructed using an electrochemical double-layer, active carbon positive electrode and a Bi2O3/porous carbon negative electrode in an alkaline solution is presented here. In this study, nanosized Bi2O3 was formed and highly dispersed into a porous active carbon material using a simple process. The characteristics of the Bi2O3 electrode as well as its electrochemical performance in the hybrid device were investigated. A highly reversible redox transit was observed in the cyclic voltammogram of the Bi2O3 loaded electrode. The transformations of Bi(III) to Bi(0) and Bi(0) to Bi(III) are clearly shown in the charge/discharge curve of Bi2O3, with potential plateaus at -0.6 and -0.5 V. The results of this experiment reveal that, with introduction of the Faradic reaction of Bi/Bi2O3, the overall specific capacity of the hybrid supercapacitor during discharge was significantly increased compared to that of a symmetric set-up.

  14. Catalase-like activity of bovine met-hemoglobin: interaction with the pseudo-catalytic peroxidation of anthracene traces in aqueous medium.

    PubMed

    Paco, Laveille; Galarneau, Anne; Drone, Jullien; Fajula, François; Bailly, Carole; Pulvin, Sylviane; Thomas, Daniel

    2009-10-01

    Hemoglobin is a member of the hemoprotein superfamily whose main role is to transport O(2) in vertebrate organisms. It has two known promiscuous enzymatic activities, peroxidase and oxygenase. Here we show for the first time that bovine hemoglobin also presents a catalase-like activity characterized by a V(max )of 344 microM/min, a K(M )of 24 mM and a k(cat) equal to 115/min. For high anthracene and hemoglobin concentrations and low hydrogen peroxide concentrations, this activity inhibits the expected oxidation of anthracene, which occurs through a peroxidase-like mechanism. Anthracene belongs to the polycyclic aromatic hydrocarbon (PAH) family whose members are carcinogenic and persistent pollutants found in industrial waste waters. Our results show that anthracene oxidation by hemoglobin and hydrogen peroxide follows a typical bi-bi ping-pong mechanism with a V(max) equal to 0.250 microM/min, K(M(H2O2) )of 80 microM, K(M(ANT)) of 1.1 microM and k(cat) of 0.17/min. The oxidation of anthracene is shown to be pseudo-catalytic because an excess of hemoglobin and hydrogen peroxide is required to make PAH completely disappear. Thus, bovine hemoglobin presents, in different degrees, all the catalytic activities of the hemoprotein group, which makes it a very interesting protein for biotechnological processes and one with which structure-activity relationships can be studied. PMID:19606432

  15. The kinetic mechanism of Human Thymidine Phosphorylase - a molecular target for cancer drug development.

    PubMed

    Deves, Candida; Rostirolla, Diana Carolina; Martinelli, Leonardo Kras Borges; Bizarro, Cristiano Valim; Santos, Diogenes Santiago; Basso, Luiz Augusto

    2014-03-01

    Human Thymidine Phosphorylase (HTP), also known as the platelet-derived endothelial cell growth factor (PD-ECGF) or gliostatin, catalyzes the reversible phosphorolysis of thymidine (dThd) to thymine and 2-deoxy-α-d-ribose-1-phosphate (2dR1P). HTP is a key enzyme in the pyrimidine salvage pathway involved in dThd homeostasis in cells. HTP is a target for anticancer drug development as its enzymatic activity promotes angiogenesis. Here, we describe cloning, expression, and purification to homogeneity of recombinant TYMP-encoded HTP. Peptide fingerprinting and the molecular mass value of the homogenous protein confirmed its identity as HTP assessed by mass spectrometry. Size exclusion chromatography showed that HTP is a dimer in solution. Kinetic studies revealed that HTP displayed substrate inhibition for dThd. Initial velocity and isothermal titration calorimetry (ITC) studies suggest that HTP catalysis follows a rapid-equilibrium random bi-bi kinetic mechanism. ITC measurements also showed that dThd and Pi binding are favorable processes. The pH-rate profiles indicated that maximal enzyme activity was achieved at low pH values. Functional groups with apparent pK values of 5.2 and 9.0 are involved in dThd binding and groups with pK values of 6.1 and 7.8 are involved in phosphate binding. PMID:24407036

  16. Lipase-catalyzed kinetic resolution of (±)-1-(2-furyl) ethanol in nonaqueous media.

    PubMed

    Devendran, Saravanan; Yadav, Ganapati D

    2014-06-01

    S-1-(2-Furyl) ethanol serves as an important chiral building block for the preparation of various natural products, fine chemicals, and is widely used in the chemical and pharmaceutical industries. In this work, lipase-catalyzed kinetic resolution of (R/S)-1-(2-furyl) ethanol using different acyl donors was investigated. Vinyl esters are good acyl donors vis-à-vis alkyl esters for kinetic resolution. Among them, vinyl acetate was found to be the best acyl donor. Different immobilized lipases such as Rhizomucor miehei lipase, Thermomyces lanuginosus lipase, and Candida antarctica lipase B were evaluated for this reaction, among which C. antarctica lipase B, immobilized on acrylic resin (Novozym 435), was found to be the best catalyst in n-heptane as solvent. The effect of various parameters was studied in a systematic manner. Maximum conversion of 47% and enantiomeric excess of the substrate (ees ) of 89% were obtained in 2 h using 5 mg of enzyme loading with an equimolar ratio of alcohol to vinyl acetate at 60 °C at a speed of 300 rpm in a batch reactor. From the analysis of progress curve and initial rate data, it was concluded that the reaction followed the ordered bi-bi mechanism with dead-end ester inhibition. Kinetic parameters were obtained by using nonlinear regression. This process is more economical, green, and easily scalable than the chemical processes. PMID:24733779

  17. Microwave assisted enzymatic kinetic resolution of (±)-1-phenyl-2-propyn-1-ol in nonaqueous media.

    PubMed

    Devendran, Saravanan; Yadav, Ganapati D

    2014-01-01

    Kinetic resolution of 1-phenyl-2-propyn-1-ol, an important chiral synthon, was studied through trans-esterification with acyl acetate to investigate synergism between microwave irradiation and enzyme catalysis. Lipases from different microbial origins were employed for the kinetic resolution of (R/S)-1-phenyl-2-propyn-1-ol, among which Candida antarctica lipase B, immobilized on acrylic resin (Novozym 435), was found to be the best catalyst in n-hexane as solvent. Vinyl acetate was the most effective among different acyl esters studied. The effect of various parameters was studied in a systematic manner. Definite synergism between microwave and enzyme was observed. The initial rate was improved around 1.28 times under microwave irradiation than conventional heating. Under optimum conditions, maximum conversion (48.78%) and high enantiomeric excess (93.25%) were obtained in 2 h. From modeling studies, it is concluded that the reaction follows the Ping-Pong bi-bi mechanism with dead end alcohol inhibition. Kinetic parameters were obtained by using nonlinear regression. This process is green, clean, and easily scalable as compared to the chemical process. PMID:24707487

  18. Microwave Assisted Enzymatic Kinetic Resolution of (±)-1-Phenyl-2-propyn-1-ol in Nonaqueous Media

    PubMed Central

    Devendran, Saravanan; Yadav, Ganapati D.

    2014-01-01

    Kinetic resolution of 1-phenyl-2-propyn-1-ol, an important chiral synthon, was studied through trans-esterification with acyl acetate to investigate synergism between microwave irradiation and enzyme catalysis. Lipases from different microbial origins were employed for the kinetic resolution of (R/S)-1-phenyl-2-propyn-1-ol, among which Candida antarctica lipase B, immobilized on acrylic resin (Novozym 435), was found to be the best catalyst in n-hexane as solvent. Vinyl acetate was the most effective among different acyl esters studied. The effect of various parameters was studied in a systematic manner. Definite synergism between microwave and enzyme was observed. The initial rate was improved around 1.28 times under microwave irradiation than conventional heating. Under optimum conditions, maximum conversion (48.78%) and high enantiomeric excess (93.25%) were obtained in 2 h. From modeling studies, it is concluded that the reaction follows the Ping-Pong bi-bi mechanism with dead end alcohol inhibition. Kinetic parameters were obtained by using nonlinear regression. This process is green, clean, and easily scalable as compared to the chemical process. PMID:24707487

  19. Assessing Pb,Zn,Cd contamination in stream sediments of south east Tehran (Iran)

    NASA Astrophysics Data System (ADS)

    Shahdadi, S.; Fayazi, F.; Yaghoobpour, A.; Rahmani, F.; Moslempour, M.

    2009-04-01

    Assessing Pb,Zn,Cd contamination in stream sediments of south east Tehran (Iran) 31 sediment samples collected from south east of Tehran around cement plant (Bibi shahrbanoo mountain) were analyzed by ICP for Pb, Zn, Cd. The samples were also investigated for mineralogy using X-ray analysis.The clay mineral assemblage encountered in the analyzed samples is composed of vermiculite, dickite, montmorillonite and kaolinite.The non-clay minerals of the mud-sized fraction are composed mainly of quartz and calcite and dolomite as major minerals with albite, hematite, muscovite as minor minerals. The measured metals correlated positively with the determined physiochemical factors such as pH, clay content, organic matter content, and carbonate content. According to the index of geoaccumulation, the sediments of the study area are considered to be strongly to very strongly polluted with respect to Pb, strongly polluted with respect to Zn, and moderatly to strongly polluted with recpect to Cd.The calculation of enrichment factors shows that the source of Pb and Zn is from antropogenic activites such as cement plant and vehicle exhausts and Cd from natural source.

  20. Unraveling the B. pseudomallei Heptokinase WcbL: From Structure to Drug Discovery

    PubMed Central

    Vivoli, Mirella; Isupov, Michail N.; Nicholas, Rebecca; Hill, Andrew; Scott, Andrew E.; Kosma, Paul; Prior, Joann L.; Harmer, Nicholas J.

    2015-01-01

    Summary Gram-negative bacteria utilize heptoses as part of their repertoire of extracellular polysaccharide virulence determinants. Disruption of heptose biosynthesis offers an attractive target for novel antimicrobials. A critical step in the synthesis of heptoses is their 1-O phosphorylation, mediated by kinases such as HldE or WcbL. Here, we present the structure of WcbL from Burkholderia pseudomallei. We report that WcbL operates through a sequential ordered Bi-Bi mechanism, loading the heptose first and then ATP. We show that dimeric WcbL binds ATP anti-cooperatively in the absence of heptose, and cooperatively in its presence. Modeling of WcbL suggests that heptose binding causes an elegant switch in the hydrogen-bonding network, facilitating the binding of a second ATP molecule. Finally, we screened a library of drug-like fragments, identifying hits that potently inhibit WcbL. Our results provide a novel mechanism for control of substrate binding and emphasize WcbL as an attractive anti-microbial target for Gram-negative bacteria. PMID:26687481

  1. Substrate-induced structures of bismuth adsorption on graphene: a first principles study.

    PubMed

    Lin, Shih-Yang; Chang, Shen-Lin; Chen, Hsin-Hsien; Su, Shu-Hsuan; Huang, Jung-Chun; Lin, Ming-Fa

    2016-07-28

    The geometric and electronic properties of Bi-adsorbed monolayer graphene, enriched by the strong effect of a substrate, are investigated by first-principles calculations. The six-layered substrate, corrugated buffer layer, and slightly deformed monolayer graphene are all simulated. Adatom arrangements are thoroughly studied by analyzing the ground-state energies, bismuth adsorption energies, and Bi-Bi interaction energies of different adatom heights, inter-adatom distance, adsorption sites, and hexagonal positions. A hexagonal array of Bi atoms is dominated by the interactions between the buffer layer and the monolayer graphene. An increase in temperature can overcome a ∼50 meV energy barrier and induce triangular and rectangular nanoclusters. The most stable and metastable structures agree with the scanning tunneling microscopy measurements. The density of states exhibits a finite value at the Fermi level, a dip at ∼-0.2 eV, and a peak at ∼-0.6 eV, as observed in the experimental measurements of the tunneling conductance. PMID:27354143

  2. Biochemical characterization of NfsA, the Escherichia coli major nitroreductase exhibiting a high amino acid sequence homology to Frp, a Vibrio harveyi flavin oxidoreductase.

    PubMed Central

    Zenno, S; Koike, H; Kumar, A N; Jayaraman, R; Tanokura, M; Saigo, K

    1996-01-01

    We identified the nfsA gene, encoding the major oxygen-insensitive nitroreductase in Escherichia coli, and determined its position on the E. coli map to be 19 min. We also purified its gene product, NfsA, to homogeneity. It was suggested that NfsA is a nonglobular protein with a molecular weight of 26,799 and is associated tightly with a flavin mononucleotide. Its amino acid sequence is highly similar to that of Frp, a flavin oxidoreductase from Vibrio harveyi (B. Lei, M. Liu, S. Huang, and S.-C. Tu, J. Bacteriol. 176:3552-3558, 1994), an observation supporting the notion that E. coli nitroreductase and luminescent-bacterium flavin reductase families are intimately related in evolution. Although no appreciable sequence similarity was detected between two E. coli nitroreductases, NfsA and NfsB, NfsA exhibited a low level of the flavin reductase activity and a broad electron acceptor specificity similar to those of NfsB. NfsA reduced nitrofurazone by a ping-pong Bi-Bi mechanism possibly to generate a two-electron transfer product. PMID:8755878

  3. The RNA shapes studio

    PubMed Central

    Janssen, Stefan; Giegerich, Robert

    2015-01-01

    Motivation: Abstract shape analysis, first proposed in 2004, allows one to extract several relevant structures from the folding space of an RNA sequence, preferable to focusing in a single structure of minimal free energy. We report recent extensions to this approach. Results: We have rebuilt the original RNAshapes as a repository of components that allows us to integrate several established tools for RNA structure analysis: RNAshapes, RNAalishapes and pknotsRG, including its recent extension pKiss. As a spin-off, we obtain heretofore unavailable functionality: e. g. with pKiss, we can now perform abstract shape analysis for structures holding pseudoknots up to the complexity of kissing hairpin motifs. The new tool pAliKiss can predict kissing hairpin motifs from aligned sequences. Along with the integration, the functionality of the tools was also extended in manifold ways. Availability and implementation: As before, the tool is available on the Bielefeld Bioinformatics server at http://bibiserv.cebitec.uni-bielefeld.de/rnashapesstudio. Contact: bibi-help@cebitec.uni-bielefeld.de PMID:25273103

  4. Immobilization of horseradish peroxidase onto kaolin.

    PubMed

    Šekuljica, Nataša Ž; Prlainović, Nevena Ž; Jovanović, Jelena R; Stefanović, Andrea B; Djokić, Veljko R; Mijin, Dušan Ž; Knežević-Jugović, Zorica D

    2016-03-01

    Kaolin showed as a very perspective carrier for the enzyme immobilization and it was used for the adsorption of horseradish peroxidase (HRP). The effects of the enzyme concentration and pH on the immobilization efficiency were studied in the reaction with pyrogallol and anthraquinone dye C.I. Acid Violet 109 (AV 109). In addition, Fourier transform infrared spectroscopy, scanning electron microscopy and analysis by Brunauer-Emmett-Teller were performed for kaolin, thermally activated kaolin and the immobilized enzyme. It has been shown that 0.1 IU of HRP-kaolin decolorized 87 % of dye solution, under the optimal conditions (pH 5.0, temperature 24 °C, dye concentration 40 mg/L and 0.2 mM of H2O2) within 40 min. The immobilized HRP decolorization follows the Ping Pong Bi-Bi mechanism with dead-end inhibition by the dye. The biocatalyst retained 35 ± 0.9 % of the initial activity after seven cycles of reuse in the decolorization reaction of AV 109 under optimal conditions in a batch reactor. The obtained kinetic parameters and reusability study confirmed improvement in performances of k-HRP compared to free, indicating that k-HRP has a great potential for environmental purposes. PMID:26747440

  5. Biosynthesis reaction mechanism and kinetics of deoxynucleoside triphosphates, dATP and dGTP.

    PubMed

    Bao, Jie; Ryu, Dewey D Y

    2005-02-20

    The enzyme reaction mechanism and kinetics for biosyntheses of deoxyadenosine triphosphate (dATP) and deoxyguanosine triphosphate (dGTP) from the corresponding deoxyadenosine diphosphate (dADP) and deoxyguanosine diphosphate (dGDP) catalyzed by pyruvate kinase were studied. A kinetic model for this synthetic reaction was developed based on a Bi-Bi random rapid equilibrium mechanism. Kinetic constants involved in this pyruvate kinase catalyzed phosphorylation reactions of deoxynucleoside diphosphates including the maximum reaction velocity, Michaelis-Menten constants, and inhibition constants for dATP and dGTP biosyntheses were experimentally determined. These kinetic constants for dATP and dGTP biosyntheses are of the same order of magnitude but significantly different between the two reactions. Kinetic constants involved in ATP and GTP biosyntheses as reported in literature are about one order of magnitude different from those involved in dATP and dGTP biosyntheses. This enzyme reaction requires Mg2+ ion and the optimal Mg2+ concentration was also determined. The experimental results showed a very good agreement with the simulation results obtained from the kinetic model developed. This kinetic model can be applied to the practical application of a pyruvate kinase reaction system for production of dATP and dGTP. There is a significant advantage of using enzymatic biosyntheses of dATP and dGTP as compared to the chemical method that has been in commercial use. PMID:15643625

  6. Acyclic monoterpene primary alcohol:NADP+ oxidoreductase of Rauwolfia serpentina cells: the key enzyme in biosynthesis of monoterpene alcohols.

    PubMed

    Ikeda, H; Esaki, N; Nakai, S; Hashimoto, K; Uesato, S; Soda, K; Fujita, T

    1991-02-01

    Acyclic monoterpene primary alcohol:NADP+ oxidoreductase, a key enzyme in the biosynthesis of monoterpene alcohols in plants, is unstable and has been only poorly characterized. However we have established conditions which stabilize the enzyme from Rauwolfia serpentina cells, and then purified it to homogeneity. It is a monomer with a molecular weight of about 44,000 and contains zinc ions. Various branched-chain allylic primary alcohols such as nerol, geraniol, and 10-hydroxygeraniol were substrates, but ethanol was inert. The enzyme exclusively requires NADP+ or NADPH as the cofactor. Steady-state kinetic studies showed that the nerol dehydrogenation proceeds by an ordered Bi-Bi mechanism. NADP+ binds the enzyme first and then NADPH is the second product released from it. Gas chromatography-mass spectrometric analysis of the reaction products showed that 10-hydroxygeraniol undergoes a reversible dehydrogenation to produce 10-oxogeraniol or 10-hydroxygeranial, which are oxidized further to give 10-oxogeranial, the direct precursor of iridodial. The enzyme has been found to exclusively transfer the pro-R hydrogen of NADPH to neral. The N-terminal sequence of the first 21 amino acids revealed no significant homology with those of various other proteins including the NAD(P)(+)-dependent alcohol dehydrogenases registered in a protein data bank. PMID:1864846

  7. Carbonyl reductase of dog liver: purification, properties, and kinetic mechanism.

    PubMed

    Hara, A; Nakayama, T; Deyashiki, Y; Kariya, K; Sawada, H

    1986-01-01

    A carbonyl reductase has been extracted into 0.5 M KCl from dog liver and purified to apparent homogeneity by a three-step procedure consisting of chromatography on CM-Sephadex, Matrex green A, and Sephadex G-100 in high-ionic-strength buffers. The enzyme is a dimer composed of two identical subunits of molecular weight 27,000. The pH optimum is 5.5 and the isoelectric point of the enzyme is 9.3. The enzyme reduces aromatic ketones and aldehydes; the aromatic ketones with adjacent medium alkyl chains are the best substrates. Quinones, ketosteroids, prostaglandins, and aliphatic carbonyl compounds are poor or inactive substrates for the enzyme. As a cofactor the enzyme utilizes NADPH, the pro-S hydrogen atom of which is transferred to the substrate. Two moles of NADPH bind to one mole of the enzyme molecule, causing a blue shift and enhancement of the cofactor fluorescence. The reductase reaction is reversible and the equilibrium constant determined at pH 7.0 is 12.8. Steady-state kinetic measurements in both directions suggest that the reaction proceeds through a di-iso ordered bi-bi mechanism. PMID:3511844

  8. A kinetic study on the Novozyme 435-catalyzed esterification of free fatty acids with octanol to produce octyl esters.

    PubMed

    Chowdhury, Avisha; Mitra, Debarati

    2015-01-01

    Octyl esters can serve as an important class of biolubricant components replacing their mineral oil counterparts. The purpose of the current work was to investigate the enzymatic esterification reaction of free fatty acids (FFA, from waste cooking oil) with octanol in a solvent-free system using a commercial lipase Novozyme 435. It was found that the esterificaton reaction followed the Ping-pong bi-bi kinetics with no inhibition by substrates or products within the studied concentration range. The maximum reaction rate was estimated to be 0.041 mol L(-1) g(-1) h(-1) . Additionally, the stability of Novozyme 435 in the current reaction system was studied by determining its activity and final conversion of FFA to esters after 12 successive utilizations. Novozyme 435 exhibited almost 100% enzyme activity up to 7 cycles of reaction and gradually decreased (by 5%) thereafter. The kinetic parameters evaluated from the study shall assist in the design of reactors for large-scale production of octyl esters from a cheap biomass source. The enzyme reusability data can further facilitate mass production by curtailing the cost of expensive enzyme consumption. PMID:26334440

  9. Impact of storm-water outfalls on sediment quality in Corpus Christi Bay, Texas, USA

    SciTech Connect

    Carr, R.S.; Montagna, P.A.; Biedenbach, J.M.; Kalke, R.; Kennicutt, M.C.; Hooten, R.; Cripe, G.

    2000-03-01

    To determine the quality of sediments and extent of contaminant impacts, a Sediment Quality Triad (SQT) study was conducted at 36 sites in the Corpus Christi Bay, Texas, USA, system. Fifteen of the 36 sites were located near storm-water outfalls, but 13 other sites (i.e., industrial and domestic outfalls, oil field-produced water discharges, and dredging activity) and eight reference sites were also evaluated. Sediment samples were collected and analyzed for physical-chemical characteristics, contaminant concentrations (metals, polycyclic aromatic hydrocarbons [PAHs], polychlorinated biphenyls [PCBs], and pesticides), toxicity, and a benthic index of biotic integrity (BIBI) composed of 10 independent metrics calculated for each site. This large data matrix was reduced using multivariate analysis to create new variables for each component representing overall means and containing most of the variance in the larger data set. The new variables were used to conduct the correlation analysis. Toxicity was significantly correlated with both chemistry and ecological responses, whereas no correlations between the benthic metrics and sediment chemistry were observed. Using the combined information from the SQT, four of the five most degraded sites were storm-water outfall sites. Although estuaries are naturally stressful environments because of salinity and temperature fluctuations, this ecosystem appears to have been compromised by anthropogenic influences similar to what has been observed for other heavily urbanized bay systems along the Texas and Gulf coast.

  10. Efficient mono-acylation of fructose by lipase-catalyzed esterification in ionic liquid co-solvents.

    PubMed

    Li, Lu; Ji, Fangling; Wang, Jingyun; Jiang, Bo; Li, Yachen; Bao, Yongming

    2015-10-30

    Fructose monoesters are eco-friendly nonionic surfactants in various applications. Selective preparation of mono-acylated fructose is challenging due to the multiple hydroxyl sites available for acylation both chemically and enzymatically. Ionic liquids (ILs) have profound impacts not only on the reaction media but also on the catalytic properties of enzymes in the acylation process. In this study, utilizing an IL co-solvent system, selective synthesis of mono-acylated fructose with lauric acid catalyzed by immobilized Candida antarctica lipase B (CALB) was investigated. The imidazolium-based ILs selected as co-solvents with 2-methyl-2-butanol (2M2B) markedly improved the ratios of monolauroyl fructose in the presence of 60% [BMIM][TfO] (v/v) and 20% [BMIM][BF4] (v/v), in which the mono-acylated fructose was 85% and 78% respectively. Based on a Ping-Pong Bi-Bi model, a kinetic equation was fitted, by which the kinetic parameters revealed that the affinity between fructose and acyl-enzyme intermediate was enhanced. The inhibition effect of fructose on free enzyme was weakened in the presence of IL co-solvents. The conformation of CALB binding substrates also changed in the co-solvent system as demonstrated by Fourier transform infrared spectra. These results demonstrated that the variation of CALB kinetic characteristics was a crucial factor for the selectivity of mono-acylation in ILs/2M2B co-solvents. PMID:26343327

  11. Lipase-catalyzed synthesis of palmitanilide: Kinetic model and antimicrobial activity study.

    PubMed

    Liu, Kuan-Miao; Liu, Kuan-Ju

    2016-01-01

    Enzymatic syntheses of fatty acid anilides are important owing to their wide range of industrial applications in detergents, shampoo, cosmetics, and surfactant formulations. The amidation reaction of Mucor miehei lipase Lipozyme IM20 was investigated for direct amidation of triacylglycerol in organic solvents. The process parameters (reaction temperature, substrate molar ratio, enzyme amount) were optimized to achieve the highest yield of anilide. The maximum yield of palmitanilide (88.9%) was achieved after 24 h of reaction at 40 °C at an enzyme concentration of 1.4% (70 mg). Kinetics of lipase-catalyzed amidation of aniline with tripalmitin has been investigated. The reaction rate could be described in terms of the Michaelis-Menten equation with a Ping-Pong Bi-Bi mechanism and competitive inhibition by both the substrates. The kinetic constants were estimated by using non-linear regression method using enzyme kinetic modules. The enzyme operational stability study showed that Lipozyme IM20 retained 38.1% of the initial activity for the synthesis of palmitanilide (even after repeated use for 48 h). Palmitanilide, a fatty acid amide, exhibited potent antimicrobial activity toward Bacillus cereus. PMID:26672452

  12. Plume Generation Zones On The Core Mantle Boundary: their origin and what they tell about how the Earth works - and how it has worked (Arthur Holmes Medal Lecture)

    NASA Astrophysics Data System (ADS)

    Burke, Kevin

    2014-05-01

    proving useful in the interpretation of mantle behaviour (For example: TPW, Steinberger and Torsvik 2008) and represent an as yet not fully utilized opportunity for improving understanding of the solid Earth. SUCCINCT REFERENCES: Burke et al. EPSLv.265, 2008, Burke et al. GRL v.39.2012, Garnero et al. GSA Mem.430, 2007, Morgan 1972 GSA Mem.132, Steinberger and Torsvik, Nature v.452, 2008, Torsvik et al Nature v.466, 2010, Wilson Can. J. Physics 1963.

  13. Inner gorge-slot canyon system produced by repeated stream incision (eastern Alps): Significance for development of bedrock canyons

    NASA Astrophysics Data System (ADS)

    Sanders, Diethard; Wischounig, Lukas; Gruber, Alfred; Ostermann, Marc

    2014-06-01

    Many inner bedrock gorges of the Alps show abrupt downstream changes in gorge width, as well as channel type and gradient, as a result of epigenetic incision of slot canyons. Many slot canyons also are associated with older gorge reaches filled with Quaternary deposits. The age of slot canyons and inner bedrock gorges, however, commonly is difficult to constrain. For the inner-bedrock gorge system of the Steinberger Ache catchment (eastern Alps), active slot canyons as well as older, abandoned gorge reaches filled with upper Würmian proglacial deposits record three phases of gorge development and slot-canyon incision. A 234U/230Th age of cement of 29.7 ± 1.8 ka in fluvial conglomerates onlapping the flank of an inner gorge fits with late Würmian valley-bottom aggradation shortly before pleniglacial conditions; in addition, the age indicates that at least the corresponding canyon reach must be older. During advance of ice streams in the buildup of the Last Glacial Maximum (LGM), the catchment was blocked, and a proglacial lake formed. Bedrock gorges submerged in that lake were filled with fluviolacustrine deposits. During the LGM, the entire catchment was overridden by ice. During post-glacial reincision, streams largely found again their preexisting inner bedrock canyons. In some areas, however, the former stream course was 'missed', and a slot canyon formed. The distribution of Pleistocene deposits, the patterns of canyon incision, and the mentioned U/Th cementation age, however, together record a further discrete phase of base-level rise and stream incision well before the LGM. The present course of Steinberger Ache and its tributaries is a patchwork of (1) slot canyons incised during post-glacial incision; (2) vestiges of slot canyons cut upon an earlier (middle to late Würmian?) cycle of base-level rise and fall; (3) reactivated reaches up to ~ 200 m in width of inner bedrock gorge that are watershed at present, and more than at least ~ 30 ka in age; and (4

  14. The Hawaiian plume: a case study for geochemists and geophysicists (Invited)

    NASA Astrophysics Data System (ADS)

    Farnetani, C. G.; Hofmann, A. W.

    2009-12-01

    Recent progress in understanding mantle plumes has been possible thanks to a tighter link between geochemical observations and geodynamic models. For the Hawaiian plume we moved from the conventional view, where entrainment of surrounding mantle governs the internal conduit structure, to one where the main process is stretching of deep-seated heterogeneities. A conduit structure with elongated, long-lived and isotopically distinct filaments is supported by geochemical observations (e.g., Abouchami et al., 2005) and by fluid dynamics numerical simulations (e.g. Farnetani and Hofmann, 2009). Another conventional view is that plumes are only weakly affected by large scale mantle convection. However, geophysical models (e.g., Steinberger 2000) predict that the Hawaiian plume should be tilted by the Pacific mantle wind. Our numerical simulations of a vigorous plume sheared by a fast moving oceanic lithosphere indeed show that the conduit is moderately tilted in the direction of plate motion. By calculating the trajectories of the upwelling material we find that a young volcano like Loihi does not sample the central part of the conduit but its upstream side. This, in turn poses a problem to another conventional view: that the highest 3He/4He ratios observed at Loihi indicate the plume center. A way to reconcile the observed 3He/4He ratios distribution in Hawaii (e.g., DePaolo et al., 2001) and the sheared plume flow is to invoke the role of carbonatite metasomatism. In a hot plume the earliest carbonatite liquid may form at 400 km depth (Dasgupta and Hirschmann, 2006) and, if helium behaves as a highly incompatible element, the liquid will sequester most of the helium from the plume center. We calculate the flow trajectories of the low density, low viscosity carbonatite liquid and find that it migrates quite vertically within the tilted plume conduit, leading to a significant off-axis displacement of the high 3He/4He ratios towards the front edge of the plume. Abouchami

  15. Mantle flow influence on the evolution of subduction systems.

    NASA Astrophysics Data System (ADS)

    Chertova, Maria; Spakman, Wim; Steinberger, Bernhard

    2016-04-01

    Evolution of the subducting slab has been widely investigated in the past two decades be means of numerical and laboratory modeling, including analysis of the factors controlling its behavior. However, until present, relatively little attention has been paid to the influence of the mantle flow. While for large subduction zones, due to the high slab buoyancy force, this effect might be small, mantle flow might be a primary factor controlling the evolution of a regional subduction zone. Here we investigate the impact of prescribed mantle flow on the evolution of both generic and real-Earth subduction models by means of 3D thermo-mechanical numerical modeling. The generic setup consists of a laterally symmetric subduction model using a 3000×2000×1000 km modeling domain with a lateral slab width varying from 500 to 1500 km. Non-linear rheology is implemented including diffusion, dislocation creep and a viscosity-limiter. To satisfy mass conservation, while implementing mantle inflow on some side boundaries, we keep other sides open (Chertova et al. 2012). To test the mantle flow influence on the dynamics of real-Earth subduction zone we adopt the numerical model from Chertova et al. (2014) for the evolution of the western Mediterranean subduction since 35 Ma. First, this model was tested with the arbitrary mantle flow prescribed on one of the four side boundaries or for the combination of two boundaries. In the last set of experiments, for side boundary conditions we use time-dependent estimates of actual mantle flow in the region based on Steinberger (2015) given for every 1 My. We demonstrate that for the western-Mediterranean subduction, the surrounding mantle flow is of second-order compared to slab buoyancy in controlling the dynamics of the subducting slab. Introducing mantle flow on the side boundaries might, however, improve the fit between the modeled and real slab imaged by tomography, although this may also trade-off with varying rheological parameters of

  16. A V2O3-ordered mesoporous carbon composite with novel peroxidase-like activity towards the glucose colorimetric assay

    NASA Astrophysics Data System (ADS)

    Han, Lei; Zeng, Lingxing; Wei, Mingdeng; Li, Chang Ming; Liu, Aihua

    2015-07-01

    It is of great scientific and practical significance to explore inorganic mimetic enzymes to replace natural enzymes due to their instability and high cost. Herein we present an interesting discovery that a V2O3-ordered mesoporous carbon composite (V2O3-OMC) has a novel peroxidase-like activity towards fast redox reaction of typical peroxidase substrates H2O2 and 2,2'-azino-bis(3-ethylbenzo-thiazoline-6-sulfonic acid) diammonium salt (ABTS). Due to the small size effect and large surface area of V2O3 nanoparticles supported by OMC, V2O3-OMC exhibited excellent catalytic performance with a kcat of 1.28 × 104 s-1, KM (ABTS) of 0.067 mM and KM (H2O2) of 0.16 mM, and a significantly higher catalytic efficiency (kcat/KM) towards the oxidation of ABTS in comparison with the natural peroxidases. Furthermore, the Ping-pong BiBi mechanism was proposed to explain the catalytic reaction by V2O3-OMC. Based on this highly active biomimetic peroxidase and the colorimetric detection of H2O2, a facile analytical method was developed to detect glucose by using V2O3-OMC and glucose oxidase, which had a wide linear range (0.01-4 mM glucose), good selectivity and reliability for successful detection of various real samples. Thus, the novel V2O3-OMC peroxidase mimetic holds great promise for broad potential applications.It is of great scientific and practical significance to explore inorganic mimetic enzymes to replace natural enzymes due to their instability and high cost. Herein we present an interesting discovery that a V2O3-ordered mesoporous carbon composite (V2O3-OMC) has a novel peroxidase-like activity towards fast redox reaction of typical peroxidase substrates H2O2 and 2,2'-azino-bis(3-ethylbenzo-thiazoline-6-sulfonic acid) diammonium salt (ABTS). Due to the small size effect and large surface area of V2O3 nanoparticles supported by OMC, V2O3-OMC exhibited excellent catalytic performance with a kcat of 1.28 × 104 s-1, KM (ABTS) of 0.067 mM and KM (H2O2) of 0.16 mM, and a

  17. The enzymology of alanine aminotransferase (AlaAT) isoforms from Hordeum vulgare and other organisms, and the HvAlaAT crystal structure.

    PubMed

    Duff, Stephen M G; Rydel, Timothy J; McClerren, Amanda L; Zhang, Wenlan; Li, Jimmy Y; Sturman, Eric J; Halls, Coralie; Chen, Songyang; Zeng, Jiamin; Peng, Jiexin; Kretzler, Crystal N; Evdokimov, Artem

    2012-12-01

    In this paper we describe the expression, purification, kinetics and biophysical characterization of alanine aminotransferase (AlaAT) from the barley plant (Hordeum vulgare). This dimeric PLP-dependent enzyme is a pivotal element of several key metabolic pathways from nitrogen assimilation to carbon metabolism, and its introduction into transgenic plants results in increased yield. The enzyme exhibits a bi-bi ping-pong reaction mechanism with a K(m) for alanine, 2-oxoglutarate, glutamate and pyruvate of 3.8, 0.3, 0.8 and 0.2 mM, respectively. Barley AlaAT catalyzes the forward (alanine-forming) reaction with a k(cat) of 25.6 s(-1), the reverse (glutamate-forming) reaction with k(cat) of 12.1 s(-1) and an equilibrium constant of ~0.5. The enzyme is also able to utilize aspartate and oxaloacetate with ~10% efficiency as compared to the native substrates, which makes it much more specific than related bacterial/archaeal enzymes (that also have lower K(m) values). We have crystallized barley AlaAT in complex with PLP and l-cycloserine and solved the structure of this complex at 2.7 Å resolution. This is the first example of a plant AlaAT structure, and it reveals a canonical aminotransferase fold similar to structures of the Thermotoga maritima, Pyrococcus furiosus, and human enzymes. This structure bridges our structural understanding of AlaAT mechanism between three kingdoms of life and allows us to shed some light on the specifics of the catalysis performed by these proteins. PMID:22750542

  18. Remaining challenges in cellular flavin cofactor homeostasis and flavoprotein biogenesis

    PubMed Central

    Giancaspero, Teresa A.; Colella, Matilde; Brizio, Carmen; Difonzo, Graziana; Fiorino, Giuseppina M.; Leone, Piero; Brandsch, Roderich; Bonomi, Francesco; Iametti, Stefania; Barile, Maria

    2015-01-01

    The primary role of the water-soluble vitamin B2 (riboflavin) in cell biology is connected with its conversion into FMN and FAD, the cofactors of a large number of dehydrogenases, oxidases and reductases involved in a broad spectrum of biological activities, among which energetic metabolism and chromatin remodeling. Subcellular localisation of FAD synthase (EC 2.7.7.2, FADS), the second enzyme in the FAD forming pathway, is addressed here in HepG2 cells by confocal microscopy, in the frame of its relationships with kinetics of FAD synthesis and delivery to client apo-flavoproteins. FAD synthesis catalyzed by recombinant isoform 2 of FADS occurs via an ordered bi-bi mechanism in which ATP binds prior to FMN, and pyrophosphate is released before FAD. Spectrophotometric continuous assays of the reconstitution rate of apo-D-aminoacid oxidase with its cofactor, allowed us to propose that besides its FAD synthesizing activity, hFADS is able to operate as a FAD “chaperone.” The physical interaction between FAD forming enzyme and its clients was further confirmed by dot blot and immunoprecipitation experiments carried out testing as a client either a nuclear lysine-specific demethylase 1 (LSD1) or a mitochondrial dimethylglycine dehydrogenase (Me2GlyDH, EC 1.5.8.4). Both enzymes carry out similar reactions of oxidative demethylation, in which tetrahydrofolate is converted into 5,10-methylene-tetrahydrofolate. A direct transfer of the cofactor from hFADS2 to apo-dimethyl glycine dehydrogenase was also demonstrated. Thus, FAD synthesis and delivery to these enzymes are crucial processes for bioenergetics and nutri-epigenetics of liver cells. PMID:25954742

  19. Remaining challenges in cellular flavin cofactor homeostasis and flavoprotein biogenesis.

    PubMed

    Giancaspero, Teresa A; Colella, Matilde; Brizio, Carmen; Difonzo, Graziana; Fiorino, Giuseppina M; Leone, Piero; Brandsch, Roderich; Bonomi, Francesco; Iametti, Stefania; Barile, Maria

    2015-01-01

    The primary role of the water-soluble vitamin B2 (riboflavin) in cell biology is connected with its conversion into FMN and FAD, the cofactors of a large number of dehydrogenases, oxidases and reductases involved in a broad spectrum of biological activities, among which energetic metabolism and chromatin remodeling. Subcellular localisation of FAD synthase (EC 2.7.7.2, FADS), the second enzyme in the FAD forming pathway, is addressed here in HepG2 cells by confocal microscopy, in the frame of its relationships with kinetics of FAD synthesis and delivery to client apo-flavoproteins. FAD synthesis catalyzed by recombinant isoform 2 of FADS occurs via an ordered bi-bi mechanism in which ATP binds prior to FMN, and pyrophosphate is released before FAD. Spectrophotometric continuous assays of the reconstitution rate of apo-D-aminoacid oxidase with its cofactor, allowed us to propose that besides its FAD synthesizing activity, hFADS is able to operate as a FAD "chaperone." The physical interaction between FAD forming enzyme and its clients was further confirmed by dot blot and immunoprecipitation experiments carried out testing as a client either a nuclear lysine-specific demethylase 1 (LSD1) or a mitochondrial dimethylglycine dehydrogenase (Me2GlyDH, EC 1.5.8.4). Both enzymes carry out similar reactions of oxidative demethylation, in which tetrahydrofolate is converted into 5,10-methylene-tetrahydrofolate. A direct transfer of the cofactor from hFADS2 to apo-dimethyl glycine dehydrogenase was also demonstrated. Thus, FAD synthesis and delivery to these enzymes are crucial processes for bioenergetics and nutri-epigenetics of liver cells. PMID:25954742

  20. Simultaneous binding of coenzyme and two ligand molecules into the active site of fungal trihydroxynaphthalene reductase.

    PubMed

    Stojan, Jure; Brunskole, Mojca; Rizner, Tea Lanisnik

    2009-03-16

    We present here a kinetic characterization of the oxidation of the artificial substrate 2,3-dihydro-2,5-dihydroxy-4H-benzopyran-4-one in the presence of NADP(+) by trihydroxynaphthalene reductase from the filamentous fungus Curvularia lunata. Although the experimental data were gathered by conventional equipment and were only available for the reaction in one direction, the analysis confirms the bi-bi reaction mechanism and yields estimates of kinetic parameters of the intermediates. It is based on an independent estimation of coenzyme binding constants and on a sequential analysis of three portions of the progress curves, from the beginning of the reaction until equilibrium is reached. First, the plateaus are used to determine the overall equilibrium constant of the non-catalyzed reaction. Then, the dissociation constants of the oxidized and reduced cofactor are estimated by titration. Subsequently, the initial parts of the progress curves are analyzed using the rate equation that is derived under combined assumptions of equilibrium and steady state. The macroscopic relations obtained are then fixed in the final progress curve analysis where the information for only two remaining rate constants is extracted from their curved portions by fitting numerically solved model-specific differential equations to the data. At pH 8, the overall equilibrium largely favours the oxidized substrate and reduced cofactor, and the activity of the holoenzyme is inhibited by high substrate concentrations. Substrate inhibition can be discriminated from true cooperativity through the effects of apigenin, a flavonoid inhibitor that is structurally similar, but larger, than the substrate used in the study. PMID:19071099

  1. Kinetic, Thermodynamic, and Structural Insight into the Mechanism of Phosphopantetheine Adenylyltransferase from Mycobacterium tuberculosis

    SciTech Connect

    Wubben, Thomas J.; Mesecar, Andrew D.

    2012-05-29

    Phosphopantetheine adenylyltransferase (PPAT) catalyzes the penultimate step in the coenzyme A (CoA) biosynthetic pathway, reversibly transferring an adenylyl group from ATP to 4'-phosphopantetheine (PhP) to form dephosphocoenzyme A. This reaction sits at the branch point between the de novo pathway and the salvage pathway, and has been shown to be a rate-limiting step in the biosynthesis of CoA. Importantly, bacterial and mammalian PPATs share little sequence homology, making the enzyme a potential target for antibiotic development. A series of steady-state kinetic, product inhibition, and direct binding studies with Mycobacterium tuberculosis PPAT (MtPPAT) was conducted and suggests that the enzyme utilizes a nonrapid-equilibrium random bi-bi mechanism. The kinetic response of MtPPAT to the binding of ATP was observed to be sigmoidal under fixed PhP concentrations, but substrate inhibition was observed at high PhP concentrations under subsaturating ATP concentrations, suggesting a preferred pathway to ternary complex formation. Negative cooperativity in the kinetic response of MtPPAT to PhP binding was observed under certain conditions and confirmed thermodynamically by isothermal titration calorimetry, suggesting the formation of an asymmetric quaternary structure during sequential ligation of substrates. Asymmetry in binding was also observed in isothermal titration calorimetry experiments with dephosphocoenzyme A and CoA. X-ray structures of MtPPAT in complex with PhP and the nonhydrolyzable ATP analogue adenosine-5'-[({alpha},{beta})-methyleno]triphosphate were solved to 1.57 {angstrom} and 2.68 {angstrom}, respectively. These crystal structures reveal small conformational changes in enzyme structure upon ligand binding, which may play a role in the nonrapid-equilibrium mechanism. We suggest that the proposed kinetic mechanism and asymmetric character in MtPPAT ligand binding may provide a means of reaction and pathway regulation in addition to that of the

  2. A V₂O₃-ordered mesoporous carbon composite with novel peroxidase-like activity towards the glucose colorimetric assay.

    PubMed

    Han, Lei; Zeng, Lingxing; Wei, Mingdeng; Li, Chang Ming; Liu, Aihua

    2015-07-21

    It is of great scientific and practical significance to explore inorganic mimetic enzymes to replace natural enzymes due to their instability and high cost. Herein we present an interesting discovery that a V2O3-ordered mesoporous carbon composite (V2O3-OMC) has a novel peroxidase-like activity towards fast redox reaction of typical peroxidase substrates H2O2 and 2,2'-azino-bis(3-ethylbenzo-thiazoline-6-sulfonic acid) diammonium salt (ABTS). Due to the small size effect and large surface area of V2O3 nanoparticles supported by OMC, V2O3-OMC exhibited excellent catalytic performance with a k(cat) of 1.28 × 10(4) s(-1), K(M) (ABTS) of 0.067 mM and K(M) (H2O2) of 0.16 mM, and a significantly higher catalytic efficiency (k(cat)/K(M)) towards the oxidation of ABTS in comparison with the natural peroxidases. Furthermore, the Ping-pong BiBi mechanism was proposed to explain the catalytic reaction by V2O3-OMC. Based on this highly active biomimetic peroxidase and the colorimetric detection of H2O2, a facile analytical method was developed to detect glucose by using V2O3-OMC and glucose oxidase, which had a wide linear range (0.01-4 mM glucose), good selectivity and reliability for successful detection of various real samples. Thus, the novel V2O3-OMC peroxidase mimetic holds great promise for broad potential applications. PMID:26099042

  3. Expression, purification and characterization of enoyl-ACP reductase II, FabK, from Porphyromonas gingivalis

    SciTech Connect

    Hevener, Kirk E.; Mehboob, Shahila; Boci, Teuta; Truong, Kent; Santarsiero, Bernard D.; Johnson, Michael E.

    2012-10-25

    The rapid rise in bacterial drug resistance coupled with the low number of novel antimicrobial compounds in the discovery pipeline has led to a critical situation requiring the expedient discovery and characterization of new antimicrobial drug targets. Enzymes in the bacterial fatty acid synthesis pathway, FAS-II, are distinct from their mammalian counterparts, FAS-I, in terms of both structure and mechanism. As such, they represent attractive targets for the design of novel antimicrobial compounds. Enoyl-acyl carrier protein reductase II, FabK, is a key, rate-limiting enzyme in the FAS-II pathway for several bacterial pathogens. The organism, Porphyromonas gingivalis, is a causative agent of chronic periodontitis that affects up to 25% of the US population and incurs a high national burden in terms of cost of treatment. P. gingivalis expresses FabK as the sole enoyl reductase enzyme in its FAS-II cycle, which makes this a particularly appealing target with potential for selective antimicrobial therapy. Herein we report the molecular cloning, expression, purification and characterization of the FabK enzyme from P. gingivalis, only the second organism from which this enzyme has been isolated. Characterization studies have shown that the enzyme is a flavoprotein, the reaction dependent upon FMN and NADPH and proceeding via a Ping-Pong Bi-Bi mechanism to reduce the enoyl substrate. A sensitive assay measuring the fluorescence decrease of NADPH as it is converted to NADP{sup +} during the reaction has been optimized for high-throughput screening. Finally, protein crystallization conditions have been identified which led to protein crystals that diffract x-rays to high resolution.

  4. Catalytic mechanism and substrate specificity of the β-subunit of the voltage-gated potassium (Kv) channel

    PubMed Central

    Tipparaju, Srinivas M.; Barski, Oleg A.; Srivastava, Sanjay; Bhatnagar, Aruni

    2008-01-01

    The β-subunits of voltage-gated potassium (Kv) channels are members of aldo-keto reductase (AKR) superfamily. These proteins regulate inactivation and membrane localization of Kv1 and Kv4 channels. The Kvβ proteins bind to pyridine nucleotides with high affinity; however, their catalytic properties remain unclear. Here we report that recombinant rat Kvβ2 catalyzes the reduction of a wide range of aldehydes and ketones. The rate of catalysis was slower (0.06 to 0.2 min−1) than that of other AKRs, but displayed the expected hyperbolic dependence on substrate concentration, with no evidence of allosteric cooperativity. Catalysis was prevented by site-directed substitution of Tyr-90 with phenylalanine, indicating that the acid-base catalytic residue, identified in other AKRs, has a conserved function in Kvβ2. The protein catalyzed the reduction of a broad range of carbonyls including aromatic carbonyls, electrophilic aldehydes and prostaglandins, phospholipid and sugar aldehydes. Little or no activity was detected with carbonyl steroids. Initial velocity profiles were consistent with an ordered bi-bi rapid-equilibrium mechanism in which NADPH binding precedes carbonyl binding. Significant primary kinetic isotope effects (2.0 – 3.1) were observed under single and multiple turnover conditions, indicating that the bond-breaking chemical step is rate-limiting. Structure-activity relationships with a series of para-substituted benzaldehydes indicated that the electronic interactions predominate during substrate binding and that no significant charge develops during the transition state. These data strengthen the view that Kvβ proteins are catalytically-active AKRs that impart redox-sensitivity to Kv channels. PMID:18672894

  5. Kinetics of acyl transfer reactions in organic media catalysed by Candida antarctica lipase B.

    PubMed

    Martinelle, M; Hult, K

    1995-09-01

    The acyl transfer reactions catalysed by Candida antartica lipase B in organic media followed a bi-bi ping-pong mechanism, with competitive substrate inhibition by the alcohols used as acyl acceptors. The effect of organic solvents on Vm and Km was investigated. The Vm values in acetonitrile was 40-50% of those in heptane. High Km values in acetonitrile compared to those in heptane could partly be explained by an increased solvation of the substrates in acetonitrile. Substrate solvation caused a 10-fold change in substrate specificity, defined as (Vm/Km)ethyl octanoate/(Vm/Km)octanoic acid, going from heptane to acetonitrile. Deacylation was the rate determining step for the acyl transfer in heptane with vinyl- and ethyl octanoate as acyl donors and (R)-2-octanol as acyl acceptor. With 1-octanol, a rate determining deacylation step in heptane was indicated using the same acyl donors. Using 1-octanol as acceptor in heptane, S-ethyl thiooctanoate had a 25- to 30-fold lower Vm/Km value and vinyl octanoate a 4-fold higher Vm/Km value than that for ethyl octanoate. The difference showed to be a Km effect for vinyl octanoate and mainly a Km effect for S-ethyl thiooctanoate. The Vm values of the esterification of octanoic acid with different alcohols was 10-30-times lower than those for the corresponding transesterification of ethyl octanoate. The low activity could be explained by a low pH around the enzyme caused by the acid or a withdrawing of active enzyme by nonproductive binding by the acid. PMID:7669809

  6. Dissecting the Catalytic Mechanism of Betaine-Homocysteine S-Methyltransferase Using Intrinsic Tryptophan Fluorescence and Site-Directed Mutagenesis

    SciTech Connect

    Castro, C.; Gratson, A.A.; Evans, J.C.; Jiracek, J.; Collinsova, M.; Ludwig, M.L.; Garrow, T.A.

    2010-03-05

    Betaine-homocysteine S-methyltransferase (BHMT) is a zinc-dependent enzyme that catalyzes the transfer of a methyl group from glycine betaine (Bet) to homocysteine (Hcy) to form dimethylglycine (DMG) and methionine (Met). Previous studies in other laboratories have indicated that catalysis proceeds through the formation of a ternary complex, with a transition state mimicked by the inhibitor S-({delta}-carboxybutyl)-l-homocysteine (CBHcy). Using changes in intrinsic tryptophan fluorescence to determine the affinity of human BHMT for substrates, products, or CBHcy, we now demonstrate that the enzyme-substrate complex reaches its transition state through an ordered bi-bi mechanism in which Hcy is the first substrate to bind and Met is the last product released. Hcy, Met, and CBHcy bind to the enzyme to form binary complexes with K{sub d} values of 7.9, 6.9, and 0.28 {micro}M, respectively. Binary complexes with Bet and DMG cannot be detected with fluorescence as a probe, but Bet and DMG bind tightly to BHMT-Hcy to form ternary complexes with K{sub d} values of 1.1 and 0.73 {micro}M, respectively. Mutation of each of the seven tryptophan residues in human BHMT provides evidence that the enzyme undergoes two distinct conformational changes that are reflected in the fluorescence of the enzyme. The first is induced when Hcy binds, and the second, when Bet binds. As predicted by the crystal structure of BHMT, the amino acids Trp44 and Tyr160 are involved in binding Bet, and Glu159 in binding Hcy. Replacing these residues by site-directed mutagenesis significantly reduces the catalytic efficiency (V{sub max}/K{sub m}) of the enzyme. Replacing Tyr77 with Phe abolishes enzyme activity.

  7. Determination of the Structure and Catalytic Mechanism of Sorghum bicolor Caffeic Acid O-Methyltransferase and the Structural Impact of Three brown midrib12 Mutations.

    PubMed

    Green, Abigail R; Lewis, Kevin M; Barr, John T; Jones, Jeffrey P; Lu, Fachuang; Ralph, John; Vermerris, Wilfred; Sattler, Scott E; Kang, ChulHee

    2014-06-19

    Using S-adenosyl-methionine as the methyl donor, caffeic acid O-methyltransferase from sorghum (Sorghum bicolor; SbCOMT) methylates the 5-hydroxyl group of its preferred substrate, 5-hydroxyconiferaldehyde. In order to determine the mechanism of SbCOMT and understand the observed reduction in the lignin syringyl-to-guaiacyl ratio of three brown midrib12 mutants that carry COMT gene missense mutations, we determined the apo-form and S-adenosyl-methionine binary complex SbCOMT crystal structures and established the ternary complex structure with 5-hydroxyconiferaldehyde by molecular modeling. These structures revealed many features shared with monocot ryegrass (Lolium perenne) and dicot alfalfa (Medicago sativa) COMTs. SbCOMT steady-state kinetic and calorimetric data suggest a random bi-bi mechanism. Based on our structural, kinetic, and thermodynamic results, we propose that the observed reactivity hierarchy among 4,5-dihydroxy-3-methoxycinnamyl (and 3,4-dihydroxycinnamyl) aldehyde, alcohol, and acid substrates arises from the ability of the aldehyde to stabilize the anionic intermediate that results from deprotonation of the 5-hydroxyl group by histidine-267. Additionally, despite the presence of other phenylpropanoid substrates in vivo, sinapaldehyde is the preferential product, as demonstrated by its low Km for 5-hydroxyconiferaldehyde. Unlike its acid and alcohol substrates, the aldehydes exhibit product inhibition, and we propose that this is due to nonproductive binding of the S-cis-form of the aldehydes inhibiting productive binding of the S-trans-form. The S-cis-aldehydes most likely act only as inhibitors, because the high rotational energy barrier around the 2-propenyl bond prevents S-trans-conversion, unlike alcohol substrates, whose low 2-propenyl bond rotational energy barrier enables rapid S-cis/S-trans-interconversion. PMID:24948836

  8. The Structural and Functional Basis of Catalysis Mediated by NAD(P)H:acceptor Oxidoreductase (FerB) of Paracoccus denitrificans

    PubMed Central

    Sedláček, Vojtěch; Klumpler, Tomáš; Marek, Jaromír; Kučera, Igor

    2014-01-01

    FerB from Paracoccus denitrificans is a soluble cytoplasmic flavoprotein that accepts redox equivalents from NADH or NADPH and transfers them to various acceptors such as quinones, ferric complexes and chromate. The crystal structure and small-angle X-ray scattering measurements in solution reported here reveal a head-to-tail dimer with two flavin mononucleotide groups bound at the opposite sides of the subunit interface. The dimers tend to self-associate to a tetrameric form at higher protein concentrations. Amino acid residues important for the binding of FMN and NADH and for the catalytic activity are identified and verified by site-directed mutagenesis. In particular, we show that Glu77 anchors a conserved water molecule in close proximity to the O2 of FMN, with the probable role of facilitating flavin reduction. Hydride transfer is shown to occur from the 4-pro-S position of NADH to the solvent-accessible si side of the flavin ring. When using deuterated NADH, this process exhibits a kinetic isotope effect of about 6 just as does the NADH-dependent quinone reductase activity of FerB; the first, reductive half-reaction of flavin cofactor is thus rate-limiting. Replacing the bulky Arg95 in the vicinity of the active site with alanine substantially enhances the activity towards external flavins that obeys the standard bi-bi ping-pong reaction mechanism. The new evidence for a cryptic flavin reductase activity of FerB justifies the previous inclusion of this enzyme in the protein family of NADPH-dependent FMN reductases. PMID:24817153

  9. The structural and functional basis of catalysis mediated by NAD(P)H:acceptor Oxidoreductase (FerB) of Paracoccus denitrificans.

    PubMed

    Sedláček, Vojtěch; Klumpler, Tomáš; Marek, Jaromír; Kučera, Igor

    2014-01-01

    FerB from Paracoccus denitrificans is a soluble cytoplasmic flavoprotein that accepts redox equivalents from NADH or NADPH and transfers them to various acceptors such as quinones, ferric complexes and chromate. The crystal structure and small-angle X-ray scattering measurements in solution reported here reveal a head-to-tail dimer with two flavin mononucleotide groups bound at the opposite sides of the subunit interface. The dimers tend to self-associate to a tetrameric form at higher protein concentrations. Amino acid residues important for the binding of FMN and NADH and for the catalytic activity are identified and verified by site-directed mutagenesis. In particular, we show that Glu77 anchors a conserved water molecule in close proximity to the O2 of FMN, with the probable role of facilitating flavin reduction. Hydride transfer is shown to occur from the 4-pro-S position of NADH to the solvent-accessible si side of the flavin ring. When using deuterated NADH, this process exhibits a kinetic isotope effect of about 6 just as does the NADH-dependent quinone reductase activity of FerB; the first, reductive half-reaction of flavin cofactor is thus rate-limiting. Replacing the bulky Arg95 in the vicinity of the active site with alanine substantially enhances the activity towards external flavins that obeys the standard bi-bi ping-pong reaction mechanism. The new evidence for a cryptic flavin reductase activity of FerB justifies the previous inclusion of this enzyme in the protein family of NADPH-dependent FMN reductases. PMID:24817153

  10. Structural flexibility modulates the activity of human glutathione transferase P1-1. Influence of a poor co-substrate on dynamics and kinetics of human glutathione transferase.

    PubMed

    Caccuri, A M; Ascenzi, P; Antonini, G; Parker, M W; Oakley, A J; Chiessi, E; Nuccetelli, M; Battistoni, A; Bellizia, A; Ricci, G

    1996-07-01

    Presteady-state and steady-state kinetics of human glutathione transferase P1-1 (EC 2.5.1.18) have been studied at pH 5.0 by using 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole, a poor co-substrate for this isoenzyme. Steady-state kinetics fits well with the simplest rapid equilibrium random sequential bi-bi mechanism and reveals a strong intrasubunit synergistic modulation between the GSH-binding site (G-site) and the hydrophobic binding site for the co-substrate (H-site); the affinity of the G-site for GSH increases about 30 times at saturating co-substrate and vice versa. Presteady-state experiments and thermodynamic data indicate that the rate-limiting step is a physical event and, probably, a structural transition of the ternary complex. Similar to that observed with 1-chloro-2, 4-dinitrobenzene (Ricci, G., Caccuri, A. M., Lo Bello, M., Rosato, N. , Mei, G., Nicotra, M., Chiessi, E., Mazzetti, A. P., and Federici, G.(1996) J. Biol. Chem. 271, 16187-16192), this event may be related to the frequency of enzyme motions. The observed low, viscosity-independent kcat value suggests that these motions are slow and diffusion-independent for an increased internal viscosity. In fact, molecular modeling suggests that the hydroxyl group of Tyr-108, which resides in helix 4, may be in hydrogen bonding distance of the oxygen atom of this new substrate, thus yielding a less flexible H-site. This effect might be transmitted to the G-site via helix 4. In addition, a new homotropic behavior exhibited by 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole is found in Cys-47 mutants revealing a structural intersubunit communication between the two H-sites. PMID:8663073

  11. Characterization and kinetic mechanism of mono- and bifunctional ornithine acetyltransferases from thermophilic microorganisms.

    PubMed

    Marc, F; Weigel, P; Legrain, C; Almeras, Y; Santrot, M; Glansdorff, N; Sakanyan, V

    2000-08-01

    The argJ gene coding for N2-acetyl-L-ornithine: L-glutamate N-acetyltransferase, the key enzyme involved in the acetyl cycle of L-arginine biosynthesis, has been cloned from thermophilic procaryotes: the archaeon Methanoccocus jannaschii, and the bacteria Thermotoga neapolitana and Bacillus stearothermophilus. Archaeal argJ only complements an Escherichia coli argE mutant (deficient in acetylornithinase, which catalyzes the fifth step in the linear biosynthetic pathway), whereas bacterial genes additionally complement an argA mutant (deficient in N-acetylglutamate synthetase, the first enzyme of the pathway). In keeping with these in vivo data the purified His-tagged ArgJ enzyme of M. jannaschii only catalyzes N2-acetylornithine conversion to ornithine, whereas T. neapolitana and B. stearothermophilus ArgJ also catalyze the conversion of glutamate to N-acetylglutamate using acetylCoA as the acetyl donor. M. jannaschii ArgJ is therefore a monofunctional enzyme, whereas T. neapolitana and B. stearothermophilus encoded ArgJ are bifunctional. Kinetic data demonstrate that in all three thermophilic organisms ArgJ-mediated catalysis follows ping-pong bi-bi kinetic mechanism. Acetylated ArgJ intermediates were detected in semireactions using [14C]acetylCoA or [14C]N2-acetyl-L-glutamate as acetyl donors. In this catalysis L-ornithine acts as an inhibitor; this amino acid therefore appears to be a key regulatory molecule in the acetyl cycle of L-arginine synthesis. Thermophilic ArgJ are synthesized as protein precursors undergoing internal cleavage to generate alpha and beta subunits which appear to assemble to alpha2beta2 heterotetramers in E. coli. The cleavage occurs between alanine and threonine residues within the highly conserved PXM-ATML motif detected in all available ArgJ sequences. PMID:10931207

  12. Enhancement of Er optical efficiency through bismuth sensitization in yttrium oxide

    SciTech Connect

    Scarangella, Adriana; Reitano, Riccardo; Franzò, Giorgia; Miritello, Maria; Priolo, Francesco

    2015-07-27

    The process of energy transfer (ET) between optically active ions has been widely studied to improve the optical efficiency of a system for different applications, from lighting and photovoltaics to silicon microphotonics. In this work, we report the influence of Bi on the Er optical emission in erbium-yttrium oxide thin films synthesized by magnetron co-sputtering. We demonstrate that this host permits to well dissolve Er and Bi ions, avoiding their clustering, and thus to stabilize the optically active Er{sup 3+} and Bi{sup 3+} valence states. In addition, we establish the ET occurrence from Bi{sup 3+} to Er{sup 3+} by the observed Bi{sup 3+} PL emission decrease and the simultaneous Er{sup 3+} photoluminescence (PL) emission increase. This was further confirmed by the coincidence of the Er{sup 3+} and Bi{sup 3+} excitation bands, analyzed by PL excitation spectroscopy. By increasing the Bi content of two orders of magnitude inside the host, though the occurrence of Bi-Bi interactions becomes deleterious for Bi{sup 3+} optical efficiency, the ET process between Bi{sup 3+} and Er{sup 3+} is still prevalent. We estimate ET efficiency of 70% for the optimized Bi:Er ratio equal to 1:3. Moreover, we have demonstrated to enhance the Er{sup 3+} effective excitation cross section by more than three orders of magnitude with respect to the direct one, estimating a value of 5.3 × 10{sup −18} cm{sup 2}, similar to the expected Bi{sup 3+} excitation cross section. This value is one of the highest obtained for Er in Si compatible hosts. These results make this material very promising as an efficient emitter for Si-compatible photonics devices.

  13. Expression, Purification and Characterization of Enoyl-ACP Reductase II, FabK, from Porphyromonas gingivalis

    PubMed Central

    Hevener, Kirk E.; Mehboob, Shahila; Boci, Teuta; Truong, Kent; Santarsiero, Bernard D.; Johnson, Michael E.

    2012-01-01

    The rapid rise in bacterial drug resistance coupled with the low number of novel antimicrobial compounds in the discovery pipeline has led to a critical situation requiring the expedient discovery and characterization of new antimicrobial drug targets. Enzymes in the bacterial fatty acid synthesis pathway, FAS-II, are distinct from their mammalian counterparts, FAS-I, in terms of both structure and mechanism. As such, they represent attractive targets for the design of novel antimicrobial compounds. Enoyl-acyl carrier protein reductase II, FabK, is a key, rate-limiting enzyme in the FAS-II pathway for several bacterial pathogens. The organism, Porphyromonas gingivalis, is a causative agent of chronic periodontitis that affects up to 25% of the U.S. population and incurs a high national burden in terms of cost of treatment. P. gingivalis expresses FabK as the sole enoyl reductase enzyme in its FAS-II cycle, which makes this a particularly appealing target with potential for selective antimicrobial therapy. Herein we report the molecular cloning, expression, purification and characterization of the FabK enzyme from P. gingivalis, only the second organism from which this enzyme has been isolated. Characterization studies have shown that the enzyme is a flavoprotein, the reaction dependent upon FMN and NADPH and proceeding via a Ping-Pong Bi-Bi mechanism to reduce the enoyl substrate. A sensitive assay measuring the fluorescence decrease of NADPH as it is converted to NADP+ during the reaction has been optimized for high-throughput screening. Finally, protein crystallization conditions have been identified which led to protein crystals that diffract x-rays to high resolution. PMID:22820244

  14. Structural comparison between the open and closed forms of citrate synthase from Thermus thermophilus HB8

    PubMed Central

    Kanamori, Eiji; Kawaguchi, Shin-ichi; Kuramitsu, Seiki; Kouyama, Tsutomu; Murakami, Midori

    2015-01-01

    The crystal structures of citrate synthase from the thermophilic eubacteria Thermus thermophilus HB8 (TtCS) were determined for an open form at 1.5 Å resolution and for closed form at 2.3 Å resolution, respectively. In the absence of ligands TtCS in the open form was crystalized into a tetragonal form with a single subunit in the asymmetric unit. TtCS was also co-crystallized with citrate and coenzyme-A to form an orthorhombic crystal with two homodimers in the asymmetric unit. Citrate and CoA are found in the active site situated between the large domain and the small domain in all subunit whereas the complex shows two distinct closed conformations, the fully closed form and partially closed form. Structural comparisons are performed to describe conformational changes associated with binding of products of TtCS. Upon binding of citrate, basic residues in the active site move toward citrate and make a hydrogen bond network in the active site, inducing a large-scale rotation of the small domain relative to the large domain. CoA is sandwiched between the small and large domains and then the cysteamine tail is inserted into the active site with a cooperative rotation around mainchain dihedrals in the hinge region connecting helices M and N. According to this rotation these helices are extended to close the active site completely. The considerable flexibility and structural rearrangements in the hinge region are crucial for an ordered bibi reaction in catalysis for microbial CSs. PMID:27493854

  15. Steady-state oxidation model by horseradish peroxidase for the estimation of the non-inactivation zone in the enzymatic removal of pentachlorophenol.

    PubMed

    Choi, Y J; Chae, H J; Kim, E Y

    1999-01-01

    A theoretical model for the rate of oxidation of pentachlorophenol (PCP) catalyzed by horseradish peroxidase (HRP), was investigated to account for the influence of hydrogen peroxide (H2O2) concentration on the catalytic activity. To evaluate the maximum allowable H2O2 concentration, a relatively simple steady-state model was developed based on the Ping-Pong Bi-Bi mechanism considering the effect of excess H2O2. Several sets of experimental data obtained from batch reactions using an equimolar concentration of H2O2 and PCP were used to estimate the kinetic parameters by a nonlinear regression method. The model profiles acquired using the estimated parameters were in good agreement with experimental data at different initial enzyme and substrate concentrations. The best-fitted parameters were used to predict the initial rate of the enzyme reaction. The model prediction was coincident with the experimental results of other studies, indicating that the proposed model could be used for the optimization of reaction conditions. The maximum allowable H2O2 concentration to prevent H2O2 inhibition was calculated from the proposed model equation: [H2O2](0,max) = (square root)KmH2O2Ki[PCP]0/KmPCP+[PCP]0. Using this equation, a curve depicting the non-inactivation zone for the two substrates (hydrogen peroxide and PCP) was plotted and it could be used for experimental design and optimal process operation. To minimize enzyme inactivation by H2O2, it was determined that the concentration of H2O2 should be lower than 2.78 mM, regardless of the stoichiometric ratio. PMID:16232630

  16. Remaining challenges in cellular flavin cofactor homeostasis and flavoprotein biogenesis

    NASA Astrophysics Data System (ADS)

    Giancaspero, Teresa Anna; Colella, Matilde; Brizio, Carmen; Difonzo, Graziana; Fiorino, Giuseppina Maria; Leone, Piero; Brandsch, Roderich; Bonomi, Francesco; Iametti, Stefania; Barile, Maria

    2015-04-01

    The primary role of the water-soluble vitamin B2 (riboflavin) in cell biology is connected with its conversion into FMN and FAD, the cofactors of a large number of dehydrogenases, oxidases and reductases involved in energetic metabolism, epigenetics, protein folding, as well as in a number of diverse regulatory processes. The problem of localisation of flavin cofactor synthesis events and in particular of the FAD synthase (EC 2.7.7.2) in HepG2 cells is addressed here by confocal microscopy in the frame of its relationships with kinetics of FAD synthesis and delivery to client apo-flavoproteins. FAD synthesis catalysed by recombinant isoform 2 of FADS occurs via an ordered bi-bi mechanism in which ATP binds prior to FMN, and pyrophosphate is released before FAD. Spectrophotometric continuous assays of the reconstitution rate of apo-D-aminoacid oxidase with its cofactor, allowed us to propose that besides its FAD synthesising activity, hFADS is able to operate as a FAD "chaperone". The physical interaction between FAD forming enzyme and its clients was further confirmed by dot blot and immunoprecipitation experiments carried out testing as a client either a nuclear or a mitochondrial enzyme that is lysine specific demethylase 1 (LSD1, EC 1.-.-.-) and dimethylglycine dehydrogenase (Me2GlyDH, EC 1.5.8.4), respectively which carry out similar reactions of oxidative demethylation, assisted by tetrahydrofolate used to form 5,10-methylene-tetrahydrofolate. A direct transfer of the cofactor from hFADS2 to apo-dimethyl glycine dehydrogenase was also demonstrated. Thus, FAD synthesis and delivery to these enzymes are crucial processes for bioenergetics and nutri-epigenetics of liver cells.

  17. Relationships Between Adolescent Sexual Outcomes and Exposure to Sex in Media: Robustness to Propensity-Based Analysis.

    PubMed

    Collins, Rebecca L; Martino, Steven C; Elliott, Marc N; Miu, Angela

    2011-03-01

    Adolescent sexual health is a substantial problem in the U.S., and two recent studies have linked adolescent sexual behavior and/or outcomes to youths' exposure to sex in the media. Both studies had longitudinal survey designs and used covariate-adjusted regression analysis. Steinberg and Monahan (2010) reanalyzed data from one of these studies (Brown et al., 2006) using a propensity-score approach, arguing that this method better addresses the possibility of unobserved confounders. Based on their reanalysis, which found no relationship between media exposure and sexual behavior, they concluded that "Adolescents' Exposure to Sexy Media Does Not Hasten the Initiation of Sexual Intercourse." We subject data from the second study (Collins et al., 2004; Chandra et al., 2008) to reanalysis using a propensity-score approach. We find only modest reductions in two of the three previously documented associations, and no reduction in the third. Based on these findings, we conclude that there is an association between exposure to sex in the media and adolescent sexual outcomes. While the evidence does not prove causality, it is sufficient to advise caution among parents, develop interventions for youth, and work with media producers and distributors to reduce youth exposure to sexual content. PMID:24839301

  18. Fabry-Perot measurements and analysis of TOW-2A liner collapse and jet formation

    SciTech Connect

    Simonson, S.C.; Winer, K.A.; Breithaupt, R.D.; Avara, G.R.; Baum, D.W.

    1996-07-01

    A TOW-2A 146 mm shaped charge was fired and observed with five beam Fabry-Perot laser velocimetry. The liner collapse velocities were measured at five lines of sight covering the outer half of the liner. A record of 8-10 {mu}s in length was obtained for each sight line The velocity records at late time differ for each location, reflecting the varying charge-to-mass ratio as the end of the liner is approached. The results were analyzed with the CALE-2D hydrodynamic simulation code. The calculations reproduce the jump-off times, the shapes of the velocity jumps and the late time velocity asymptotes, but they underestimate the jump-off velocities by 6-7%. The calculations show that there exist no features in the velocity records that require spallation to account for them. Rather, the standard Steinberg-Guinan material model adequately accounts for the response of this copper liner to LX-14.

  19. Modelling evolution of asteroid's rotation due to the YORP effect

    NASA Astrophysics Data System (ADS)

    Golubov, Oleksiy; Lipatova, Veronika; Scheeres, Daniel J.

    2016-05-01

    The Yarkovsky--O'Keefe--Radzievskii--Paddack (or YORP) effect is influence of light pressure on rotation of asteroids. It is the most important factor for evolution of rotation state of small asteroids, which can drastically alter their rotation rate and obliquity over cosmologic timescales.In the poster we present our program, which calculates evolution of ratation state of small asteroids subject to the YORP effect. The program accounts for both axial and obliquity components of YORP, takes into account the thermal inertia of the asteroid's soil, and the tangential YORP. The axial component of YORP is computed using the model by Steinberg and Sari (AJ, 141, 55). The thermal inertia is accounted for in the framework of Golubov et al. 2016 (MNRAS, stw540). Computation of the tangential YORP is based on a siple analytical model, whose applicability is verified via comparison to exact numeric simulations.We apply the program to different shape models of asteroids, and study coupled evolution of their rotation rate and obliquity.

  20. Phylogeny and genetic diversity of palolo worms (Palola, Eunicidae) from the tropical North Pacific and the Caribbean.

    PubMed

    Schulze, Anja

    2006-02-01

    Palolo worms (Palola, Eunicidae) are best known for their annual mass spawnings, or "risings," in the South Pacific. Palola currently contains 14 morphologically similar species, mostly from shallow tropical waters. In this study, 60 specimens of Palola from nine locations in the tropical North Pacific and the Caribbean were sequenced for the two mitochondrial markers cytochrome c oxidase subunit I and 16S ribosomal RNA to infer phylogenetic relationships, genetic diversity, and phylogeography within the taxon. Phylogenetic analysis was performed using Bayesian statistics and parsimony. Vouchers of the same specimens were examined morphologically. Two major clades (A and B) can be distinguished within the monophyletic Palola. A number of individuals in clade B bear rows of ventral eyespots in the posterior body region, typical for swarming P. viridis and probably a synapomorphy for clade B. No morphological synapomorphy was found for clade A. Haplotypes from divergent clades often co-occur in the same location. Some haplotypes are geographically widespread, in one case covering the entire east-west expansion of the tropical Pacific. These results imply that despite the apparent absence of teleplanic larvae in eunicid polychaetes, long-distance dispersal is possible in at least some lineages of Palola. With the first taste of palolo I understood the Samoans' love for it. Certainly it suggested a salty caviar, but with something added, a strong, rich whiff of the mystery and fecundity of the ocean depths. -R. Steinberg. Pacific and Southeast Asian cooking. Time-Life Books, New York, 1970. PMID:16501062

  1. Bilocal current densities and mean trajectories in a Young interferometer with two Gaussian slits and two detectors

    SciTech Connect

    Withers, L. P.; Narducci, F. A.

    2015-06-15

    The recent single-photon double-slit experiment of Steinberg et al., based on a weak measurement method proposed by Wiseman, showed that, by encoding the photon’s transverse momentum behind the slits into its polarization state, the momentum profile can subsequently be measured on average, from a difference of the separated fringe intensities for the two circular polarization components. They then integrated the measured average velocity field, to obtain the average trajectories of the photons enroute to the detector array. In this paper, we propose a modification of their experiment, to demonstrate that the average particle velocities and trajectories change when the mode of detection changes. The proposed experiment replaces a single detector by a pair of detectors with a given spacing between them. The pair of detectors is configured so that it is impossible to distinguish which detector received the particle. The pair of detectors is then analogous to the simple pair of slits, in that it is impossible to distinguish which slit the particle passed through. To establish the paradoxical outcome of the modified experiment, the theory and explicit three-dimensional formulas are developed for the bilocal probability and current densities, and for the average velocity field and trajectories as the particle wavefunction propagates in the volume of space behind the Gaussian slits. Examples of these predicted results are plotted. Implementation details of the proposed experiment are discussed.

  2. Fine Tuning of Tissues' Viscosity and Surface Tension through Contractility Suggests a New Role for α-Catenin

    PubMed Central

    Stirbat, Tomita Vasilica; Mgharbel, Abbas; Bodennec, Selena; Ferri, Karine; Mertani, Hichem C.; Rieu, Jean-Paul; Delanoë-Ayari, Hélène

    2013-01-01

    What governs tissue organization and movement? If molecular and genetic approaches are able to give some answers on these issues, more and more works are now giving a real importance to mechanics as a key component eventually triggering further signaling events. We chose embryonic cell aggregates as model systems for tissue organization and movement in order to investigate the origin of some mechanical constraints arising from cells organization. Steinberg et al. proposed a long time ago an analogy between liquids and tissues and showed that indeed tissues possess a measurable tissue surface tension and viscosity. We question here the molecular origin of these parameters and give a quantitative measurement of adhesion versus contractility in the framework of the differential interfacial tension hypothesis. Accompanying surface tension measurements by angle measurements (at vertexes of cell-cell contacts) at the cell/medium interface, we are able to extract the full parameters of this model: cortical tensions and adhesion energy. We show that a tunable surface tension and viscosity can be achieved easily through the control of cell-cell contractility compared to cell-medium one. Moreover we show that -catenin is crucial for this regulation to occur: these molecules appear as a catalyser for the remodeling of the actin cytoskeleton underneath cell-cell contact, enabling a differential contractility between the cell-medium and cell-cell interface to take place. PMID:23390488

  3. Multiple traumas, postelection violence, and posttraumatic stress among impoverished Kenyan youth.

    PubMed

    Harder, Valerie S; Mutiso, Victoria N; Khasakhala, Lincoln I; Burke, Heather M; Ndetei, David M

    2012-02-01

    Research on posttraumatic stress disorder (PTSD) among youth has focused on specific subgroups from developed countries. Most of the world's youth and war-like violence, however, is concentrated in developing countries, yet there is limited mental health data within affected countries. This study focused on a random community-based sample of 552 impoverished youth ages 6-18 within an informal settlement in Nairobi, Kenya, which experienced war-like violence for a month following the contested presidential election of 2007. Six months after the violence ended, 99 (18%) had PTSD according to the UCLA PTSD Reaction Index (Steinberg, Brymer, Decker, & Pynoos, 2004), and an additional 18 (3%) were found to have partial PTSD due to high overall scores. Kenyan psychologists conducted diagnostic interviews and found the positive predictive value of the assessment tool to be 72% in this sample; the confirmed prevalence was 12%. Similar to other studies worldwide, Criterion C (avoidance) was the limiting factor for diagnosing PTSD according to the DSM-IV-TR, and parent-child agreement was at best fair. The number of traumatic experiences was strongly associated with PTSD outcomes. Differences due to age or sex were not found. The findings indicate the need for universal mental health services for trauma-exposed youth and their families in the impoverished informal settlements of Nairobi, Kenya. PMID:22354509

  4. Cookoff Response of PBXN-109: Material Characterization and ALE3D Thermal Predictions

    SciTech Connect

    McClelland, M A; Tran, T D; Cunningham, B J; Weese, R K; Maienschein, J L

    2001-05-29

    Materials properties measurements are made for the RDX-based explosive, PBXN-109, and initial ALE3D model predictions are given for the cookoff temperature in a U.S. Navy test. This work is part of an effort in the U.S. Navy and Department of Energy (DOE) laboratories to understand the thermal explosion behavior of this material. Benchmark cookoff experiments are being performed by the U.S. Navy to validate DOE materials models and computer codes. The ALE3D computer code can model the coupled thermal, mechanical, and chemical behavior of heating, ignition, and explosion in cookoff tests. In our application, a standard three-step step model is selected for the chemical kinetics. The strength behavior of the solid constituents is represented by a Steinberg-Guinan model while polynomial and gamma-law expressions are used for the Equation Of State (EOS) for the solid and gas species, respectively. Materials characterization measurements are given for thermal expansion, heat capacity, shear modulus, bulk modulus, and One-Dimensional-Time-to-Explosion (ODTX). These measurements and those of the other project participants are used to determine parameters in the ALE3D chemical, mechanical, and thermal models. Time-dependent, two-dimensional results are given for the temperature and material expansion. The results show predicted cookoff temperatures slightly higher than the measured values.

  5. Cookoff Response of PBXN-109: Material Characterization and ALE3D Thermal Predictions

    SciTech Connect

    McClelland, M A; Tran, T D; Cunningham, B J; Weese, R K; Maienschein, J L

    2001-08-21

    Materials properties measurements are made for the RDX-based explosive, PBXN-109, and initial ALE3D model predictions are given for the cookoff temperature in a U.S. Navy test. This work is part of an effort in the U.S. Navy and Department of Energy (DOE) laboratories to understand the thermal explosion behavior of this material. Benchmark cookoff experiments are being performed by the U.S. Navy to validate DOE materials models and computer codes. The ALE3D computer code can model the coupled thermal, mechanical, and chemical behavior of heating, ignition, and explosion in cookoff tests. In our application, a standard three-step step model is selected for the chemical kinetics. The strength behavior of the solid constituents is represented by a Steinberg-Guinan model while polynomial and gamma-law expressions are used for the Equation Of State (EOS) for the solid and gas species, respectively. Materials characterization measurements are given for thermal expansion, heat capacity, shear modulus, bulk modulus, and One-Dimensional-Time-to-Explosion (ODTX). These measurements and those of the other project participants are used to determine parameters in the ALE3D chemical, mechanical, and thermal models. Time-dependent, two-dimensional results are given for the temperature and material expansion. The results show predicted cookoff temperatures slightly higher than the measured values.

  6. 2169 steel waveform measurements for equation of state and strength determination

    NASA Astrophysics Data System (ADS)

    Furnish, M. D.; Alexander, C. S.; Brown, J. L.; Reinhart, W. D.

    2014-01-01

    In support of efforts to develop multiscale models of a variety of materials, we have performed a set of eleven gas gun impact experiments on 2169 steel, a high-strength austenitic stainless steel. These experiments provided carefully controlled shock, reshock, and release velocimetry data, with initial shock stresses ranging from 10 to 50 GPa. Both windowed and free-surface measurements on samples ranging in thickness from 1 to 5 mm were made to increase the utility of the data set. Target physical phenomena included the elastic/plastic transition (Hugoniot elastic limit), the Hugoniot, any phase transition phenomena, and the release/reshock paths (windowed and free-surface), with associated strength information. The Hugoniot is nearly linear in US-up space. Reshock tests with explosively welded impactors produced clean results, by contrast with earlier reshock tests with glued impactors which showed gap signatures. The free-surface samples, which were steps on a single piece of steel, showed lower wavespeeds for thin (1 mm) samples than for thicker (2 or 4 mm) samples. A preliminary strength analysis suggests the flow strength increases with stress from ˜1 GPa to ˜2.5 GPa over this range, consistent with other recent work but about 25% above the Steinberg model.

  7. Relationships Between Adolescent Sexual Outcomes and Exposure to Sex in Media: Robustness to Propensity-Based Analysis

    PubMed Central

    Collins, Rebecca L.; Martino, Steven C.; Elliott, Marc N.; Miu, Angela

    2013-01-01

    Adolescent sexual health is a substantial problem in the U.S., and two recent studies have linked adolescent sexual behavior and/or outcomes to youths' exposure to sex in the media. Both studies had longitudinal survey designs and used covariate-adjusted regression analysis. Steinberg and Monahan (2010) reanalyzed data from one of these studies (Brown et al., 2006) using a propensity-score approach, arguing that this method better addresses the possibility of unobserved confounders. Based on their reanalysis, which found no relationship between media exposure and sexual behavior, they concluded that “Adolescents' Exposure to Sexy Media Does Not Hasten the Initiation of Sexual Intercourse.” We subject data from the second study (Collins et al., 2004; Chandra et al., 2008) to reanalysis using a propensity-score approach. We find only modest reductions in two of the three previously documented associations, and no reduction in the third. Based on these findings, we conclude that there is an association between exposure to sex in the media and adolescent sexual outcomes. While the evidence does not prove causality, it is sufficient to advise caution among parents, develop interventions for youth, and work with media producers and distributors to reduce youth exposure to sexual content. PMID:24839301

  8. The mechanics of cellular compartmentalization as a model for tumor spreading

    NASA Astrophysics Data System (ADS)

    Fritsch, Anatol; Pawlizak, Steve; Zink, Mareike; Kaes, Josef A.

    2012-02-01

    Based on a recently developed surgical method of Michael H"ockel, which makes use of cellular confinement to compartments in the human body, we study the mechanics of the process of cell segregation. Compartmentalization is a fundamental process of cellular organization and occurs during embryonic development. A simple model system can demonstrate the process of compartmentalization: When two populations of suspended cells are mixed, this mixture will eventually segregate into two phases, whereas mixtures of the same cell type will not. In the 1960s, Malcolm S. Steinberg formulated the so-called differential adhesion hypothesis which explains the segregation in the model system and the process of compartmentalization by differences in surface tension and adhesiveness of the interacting cells. We are interested in to which extend the same physical principles affect tumor growth and spreading between compartments. For our studies, we use healthy and cancerous breast cell lines of different malignancy as well as primary cells from human cervix carcinoma. We apply a set of techniques to study their mechanical properties and interactions. The Optical Stretcher is used for whole cell rheology, while Cell-cell-adhesion forces are directly measured with a modified AFM. In combination with 3D segregation experiments in droplet cultures we try to clarify the role of surface tension in tumor spreading.

  9. Tunneling Time and Weak Measurement in Strong Field Ionization

    NASA Astrophysics Data System (ADS)

    Zimmermann, Tomáš; Mishra, Siddhartha; Doran, Brent R.; Gordon, Daniel F.; Landsman, Alexandra S.

    2016-06-01

    Tunneling delays represent a hotly debated topic, with many conflicting definitions and little consensus on when and if such definitions accurately describe the physical observables. Here, we relate these different definitions to distinct experimental observables in strong field ionization, finding that two definitions, Larmor time and Bohmian time, are compatible with the attoclock observable and the resonance lifetime of a bound state, respectively. Both of these definitions are closely connected to the theory of weak measurement, with Larmor time being the weak measurement value of tunneling time and Bohmian trajectory corresponding to the average particle trajectory, which has been recently reconstructed using weak measurement in a two-slit experiment [S. Kocsis, B. Braverman, S. Ravets, M. J. Stevens, R. P. Mirin, L. K. Shalm, and A. M. Steinberg, Science 332, 1170 (2011)]. We demonstrate a big discrepancy in strong field ionization between the Bohmian and weak measurement values of tunneling time, and we suggest this arises because the tunneling time is calculated for a small probability postselected ensemble of electrons. Our results have important implications for the interpretation of experiments in attosecond science, suggesting that tunneling is unlikely to be an instantaneous process.

  10. Empathy for Pain from Adolescence through Adulthood: An Event-Related Brain Potential Study.

    PubMed

    Mella, Nathalie; Studer, Joseph; Gilet, Anne-Laure; Labouvie-Vief, Gisela

    2012-01-01

    Affective and cognitive empathy are traditionally differentiated, the affective component being concerned with resonating with another's emotional state, whereas the cognitive component reflects regulation of the resulting distress and understanding of another's mental states (see Decety and Jackson, 2004 for a review). Adolescence is a critical period for the development of cognitive control processes necessary to regulate affective processes: it is only in young adulthood that these control processes achieve maturity (Steinberg, 2005). Thus, one should expect adolescents to show greater automatic empathy than young adults. The present study aimed at exploring the neural correlates of affective (automatic) and cognitive empathy for pain from adolescence to young adulthood. With this aim, Event Related Potentials (ERPs) were recorded in 32 participants (aged 11-39) in a task designed to dissociate these components. ERPs results showed an early automatic fronto-central response to pain (that was not modulated by task demand) and a late parietal response to painful stimuli modulated by attention to pain cues. Adolescents exhibited earlier automatic responses to painful situations than young adults did and showed greater activity in the late cognitive component even when viewing neutral stimuli. Results are discussed in the context of the development of regulatory abilities during adolescence. PMID:23189065

  11. Free vascularised fibular grafting with OsteoSet®2 demineralised bone matrix versus autograft for large osteonecrotic lesions of the femoral head.

    PubMed

    Feng, Yong; Wang, Shanzhi; Jin, Dongxu; Sheng, Jiagen; Chen, Shengbao; Cheng, Xiangguo; Zhang, Changqing

    2011-04-01

    The aim of this study was to compare the safety and efficacy of OsteoSet®2 DBM with autologous cancellous bone in free vascularised fibular grafting for the treatment of large osteonecrotic lesions of the femoral head. Twenty-four patients (30 hips) with large osteonecrotic lesions of the femoral head (stage IIC in six hips, stage IIIC in 14, and stage IVC in ten, according to the classification system of Steinberg et al.) underwent free vascularised fibular grafting with OsteoSet®2 DBM. This group was retrospectively matched to a group of 24 patients (30 hips) who underwent free vascularised fibular grafting with autologous cancellous bone during the same time period according to the aetiology, stage, and size of the lesion and the mean preoperative Harris hip score. A prospective case-controlled study was then performed with a mean follow-up duration of 26 months. The results show no statistically significant differences between the two groups in overall clinical outcome or the radiographic assessment. Furthermore, no adverse events related to the use of the OsteoSet®2 DBM were observed. The results demonstrate that OsteoSet®2 DBM combined with autograft bone performs equally as well as that of autologous bone alone. Therefore, OsteoSet®2 DBM can be used as a safe and effective graft extender in free vascularised fibular grafting for large osteonecrotic lesions of the femoral head. PMID:20012040

  12. Quark Matter 2011 (QM11) Quark Matter 2011 (QM11)

    NASA Astrophysics Data System (ADS)

    2011-12-01

    International Advisory Committee Antinori, FedericoPaic, Guy Braun-Munzinger, PeterPajares, Carlos Cifarelli, LuisaPeitzmann, Thomas Erazmus, BarbaraRedlich, Krzysztof Eskola, KariRiccati, Lodovico Gaardhøje, Jens JørgenRoland, Gunther Gale, CharlesRoy, Christelle Gelis, FrancoisSchukraft, Jürgen Giubellino, PaoloSinha, Bikash Greiner, CarstenSrivastava, Dinesh Gyulassy, MiklosStachel, Johanna Harris, JohnSteinberg, Peter Hatsuda, TetsuoStroth, Joachim Heinz, UlrichSugitate, Toru Jacak, BarbaraTserruya, Itzhak Karsch, FrithjofVelkovska, Julia Kharzeev, DimaWang, Enke Kodama, TakeshiWang, Xin, Nian Lévai, PéterWessels, Johannes Manko, VladislavXu, Nu Müller, BerndtZajc, William Ollitrault, Jean-Yves Organizing Committee Arleo, FrancoisDupieux, Pascal Bastid, NicoleFurget, Christophe Bourgeois, Marie-LaureGranier de Cassagnac, Raphael Bregant, MarcoGuernane, Rachid Carminati, FedericoHervet, Carnita Castillo, JavierKuhn, Christian Cheynis, BrigitteOlivier, Nathalie Conesa, DelValle, Zaida Connor, MichelleRenshall, Lucy Crochet, PhilippeSuire, Christophe Delagrange, HuguesTihinen, Ulla Program Committee Schutz, Yves (Chair)Baldisseri, Alberto Wiedemann, Urs (co-Chair)Safarik, Karel Aurenche, Patrick

  13. Modeling Propagation of Shock Waves in Metals

    SciTech Connect

    Howard, W M; Molitoris, J D

    2005-08-19

    We present modeling results for the propagation of strong shock waves in metals. In particular, we use an arbitrary Lagrange Eulerian (ALE3D) code to model the propagation of strong pressure waves (P {approx} 300 to 400 kbars) generated with high explosives in contact with aluminum cylinders. The aluminum cylinders are assumed to be both flat-topped and have large-amplitude curved surfaces. We use 3D Lagrange mechanics. For the aluminum we use a rate-independent Steinberg-Guinan model, where the yield strength and shear modulus depend on pressure, density and temperature. The calculation of the melt temperature is based on the Lindermann law. At melt the yield strength and shear modulus is set to zero. The pressure is represented as a seven-term polynomial as a function of density. For the HMX-based high explosive, we use a JWL, with a program burn model that give the correct detonation velocity and C-J pressure (P {approx} 390 kbars). For the case of the large-amplitude curved surface, we discuss the evolving shock structure in terms of the early shock propagation experiments by Sakharov.

  14. Tunneling Time and Weak Measurement in Strong Field Ionization.

    PubMed

    Zimmermann, Tomáš; Mishra, Siddhartha; Doran, Brent R; Gordon, Daniel F; Landsman, Alexandra S

    2016-06-10

    Tunneling delays represent a hotly debated topic, with many conflicting definitions and little consensus on when and if such definitions accurately describe the physical observables. Here, we relate these different definitions to distinct experimental observables in strong field ionization, finding that two definitions, Larmor time and Bohmian time, are compatible with the attoclock observable and the resonance lifetime of a bound state, respectively. Both of these definitions are closely connected to the theory of weak measurement, with Larmor time being the weak measurement value of tunneling time and Bohmian trajectory corresponding to the average particle trajectory, which has been recently reconstructed using weak measurement in a two-slit experiment [S. Kocsis, B. Braverman, S. Ravets, M. J. Stevens, R. P. Mirin, L. K. Shalm, and A. M. Steinberg, Science 332, 1170 (2011)]. We demonstrate a big discrepancy in strong field ionization between the Bohmian and weak measurement values of tunneling time, and we suggest this arises because the tunneling time is calculated for a small probability postselected ensemble of electrons. Our results have important implications for the interpretation of experiments in attosecond science, suggesting that tunneling is unlikely to be an instantaneous process. PMID:27341232

  15. ALE3D Model Predictions and Materials Characterization for the Cookoff Response of PBXN-109

    SciTech Connect

    McClelland, M A; Maienschein, J L; Nichols, A L; Wardell, J F; Atwood, A I; Curran, P O

    2002-03-19

    ALE3D simulations are presented for the thermal explosion of PBXN-109 (RDX, AI, HTPB, DOA) in support of an effort by the U. S. Navy and Department of Energy (DOE) to validate computational models. The U.S. Navy is performing benchmark tests for the slow cookoff of PBXN-109 in a sealed tube. Candidate models are being tested using the ALE3D code, which can simulate the coupled thermal, mechanical, and chemical behavior during heating, ignition, and explosion. The strength behavior of the solid constituents is represented by a Steinberg-Guinan model while polynomial and gamma-law expressions are used for the Equation Of State (EOS) for the solid and gas species, respectively. A void model is employed to represent the air in gaps. ALE3D model 'parameters are specified using measurements of thermal and mechanical properties including thermal expansion, heat capacity, shear modulus, and bulk modulus. A standard three-step chemical kinetics model is used during the thermal ramp, and a pressure-dependent burn front model is employed during the rapid expansion. Parameters for the three-step kinetics model are specified using measurements of the One-Dimensional-Time-to-Explosion (ODTX), while measurements for burn rate of pristine and thermally damaged material are employed to determine parameters in the burn front model. Results are given for calculations in which heating, ignition, and explosion are modeled in a single simulation. We compare model results to measurements for the cookoff temperature and tube wall strain.

  16. Pubertal Development and Behavior: Hormonal Activation of Social and Motivational Tendencies

    PubMed Central

    Dahl, Ronald E.; Forbes, Erika E.

    2010-01-01

    Adolescence is a time of dramatic changes including rapid physical growth, the onset of sexual maturation, the activation of new drives and motivations, and a wide array of social and affective changes and challenges. This review focuses on behavioral changes in this interval and is organized by the claim that a key set of these adolescent changes are part of a more general re-orientation of social behavior. More specifically we hypothesize that pubertal maturation is associated with the activation of social and motivational tendencies, which in turn influence behavior and emotion in adolescence depending upon interactions with social context. We focus on evidence for two examples of these motivational changes: 1) increases in sensation seeking (motivational tendency to want to experience high-intensity, exciting experiences) and 2) stronger natural interest in—and pursuit of—contact with peers and potential romantic partners. We consider how these motivational changes contribute to the broader social re-orientation of adolescence, including exploration of social experiences, the development of skills and knowledge relevant to taking on adult social roles, individuation from family, and the establishment of an individual identity, all of which represent core developmental tasks during this period in the life span (Blakemore, 2008; Dahl & Spear, 2004; Steinberg & Morris, 2000). The paper also emphasizes the importance of investigating and understanding the direct influences of puberty on behavior and disentangling these from the broader set of changes during adolescent development. PMID:19942334

  17. Two-photon dual channel fluctuation correlation spectroscopy: Theory and application

    NASA Astrophysics Data System (ADS)

    Eid, John Safwat

    Fluctuation correlation spectroscopy (FCS) is a non-perturbative method used to gain molecular information from stochastic processes such as Brownian motion (Magde, Elson et al. 1972). Dual channel FCS allows for the investigation of static (molecular associations) and kinetic (protein dynamics) parameters of interaction between two species. This technique is able to quantitate in vivo molecular interactions that are critical for cellular study. Data acquisition hardware was built which allows 25 ns time resolution and records the entire photon sequence using a hardware data compression technique. This allows multiple analysis to be performed (i.e. photon counting histogram (Muller, Chen et al. 1999), moment analysis, etc.) The basic theory and simulation of oligomer size effect on dual channel FCS data was done to allow interpretation of an in vivo study involving the amount of aggregation between different somatostatin membrane receptors. The cross-correlation, in combination with Forster resonance energy transfer (FRET), provides a more elegant method to study protein dynamics than the equivalent quenching experiment involving only one channel of detection (Haas and Steinberg 1984). The extra relaxation is present as an extra hump in the autocorrelation and as an anti-correlation for the cross-correlation. This signature anti-correlation differentiates this process from others such as triplet state, rotational diffusion, quenching, etc. In vitro confirmation is provided through studies of ribosome and cameleon proteins.

  18. Three Dimensional Dirac Semimetals

    NASA Astrophysics Data System (ADS)

    Zaheer, Saad

    2014-03-01

    Dirac points on the Fermi surface of two dimensional graphene are responsible for its unique electronic behavior. One can ask whether any three dimensional materials support similar pseudorelativistic physics in their bulk electronic spectra. This possibility has been investigated theoretically and is now supported by two successful experimental demonstrations reported during the last year. In this talk, I will summarize the various ways in which Dirac semimetals can be realized in three dimensions with primary focus on a specific theory developed on the basis of representations of crystal spacegroups. A three dimensional Dirac (Weyl) semimetal can appear in the presence (absence) of inversion symmetry by tuning parameters to the phase boundary separating a bulk insulating and a topological insulating phase. More generally, we find that specific rules governing crystal symmetry representations of electrons with spin lead to robust Dirac points at high symmetry points in the Brillouin zone. Combining these rules with microscopic considerations identifies six candidate Dirac semimetals. Another method towards engineering Dirac semimetals involves combining crystal symmetry and band inversion. Several candidate materials have been proposed utilizing this mechanism and one of the candidates has been successfully demonstrated as a Dirac semimetal in two independent experiments. Work carried out in collaboration with: Julia A. Steinberg, Steve M. Young, J.C.Y. Teo, C.L. Kane, E.J. Mele and Andrew M. Rappe.

  19. Hereditary pancreatitis associated with a balanced translocation (5q;11p)

    SciTech Connect

    Dasouki, J.J.; Summar, M.L.; Mixon, C.

    1994-09-01

    Dominantly inherited pancreatitis was first described by Comfort and Steinberg in 1952. It is estimated to account for <1% of all childhood pancreatitis cases. Patients as young as 17 months of age were reported. Presentation varies from acute abdominal pain mimicking familial Mediterranean fever to more chronic steatorrhea causing malabsorption. Urinary excretion of cystine in both affected and unaffected family members is an unexplained feature. Our 37 year old, G{sub 1}P{sub 0{minus}1} proband is known to have familial pancreatitis which complicated her current pregnancy. Family history was also positive in her mother and a sister who has a 12 year old daughter with recurrent abdominal pain. The proband sought genetic counselling because her amniocentesis showed a male fetus with an apparently balanced reciprocal translocation: t(5;11)(q13;p15). A detailed fetal ultrasound examination failed to show any abnormality. On chromosomal analysis, the proband was found to have a similar translocation. Her plasma aminogram was normal, however the spot and 24 hour urine aminograms demonstrated generalized aminoaciduria. This is the first report of hereditary pancreatitis with a segregating balanced autosomal translocation which may be etiologically important. In addition, unlike what was described previously, the aminoaciduria was generalized and nonspecific. Molecular analysis of the genes located in the breakpoint region may prove to be helpful in identifying the responsible gene and the delineation of the pathogenesis of this developmental disorder.

  20. A fast approach for accurate content-adaptive mesh generation.

    PubMed

    Yang, Yongyi; Wernick, Miles N; Brankov, Jovan G

    2003-01-01

    Mesh modeling is an important problem with many applications in image processing. A key issue in mesh modeling is how to generate a mesh structure that well represents an image by adapting to its content. We propose a new approach to mesh generation, which is based on a theoretical result derived on the error bound of a mesh representation. In the proposed method, the classical Floyd-Steinberg error-diffusion algorithm is employed to place mesh nodes in the image domain so that their spatial density varies according to the local image content. Delaunay triangulation is next applied to connect the mesh nodes. The result of this approach is that fine mesh elements are placed automatically in regions of the image containing high-frequency features while coarse mesh elements are used to represent smooth areas. The proposed algorithm is noniterative, fast, and easy to implement. Numerical results demonstrate that, at very low computational cost, the proposed approach can produce mesh representations that are more accurate than those produced by several existing methods. Moreover, it is demonstrated that the proposed algorithm performs well with images of various kinds, even in the presence of noise. PMID:18237961

  1. Frequency importance functions for a feature recognition test material.

    PubMed

    Duggirala, V; Studebaker, G A; Pavlovic, C V; Sherbecoe, R L

    1988-06-01

    The relative importance of different parts of the auditory spectrum to recognition of the Diagnostic Rhyme Test (DRT) and its six speech feature subtests was determined. Three normal hearing subjects were tested twice in each of 70 experimental conditions. The analytical procedures of French and Steinberg [J. Acoust. Soc. Am. 19, 90-119 (1947)] were applied to the data to derive frequency importance functions for each of the DRT subtests and the test as a whole over the frequency range 178-8912 Hz. For the DRT as a whole, the low frequencies were found to be more important than is the case for nonsense syllables. Importance functions for the feature subtests also differed from those for nonsense syllables and from each other as well. These results suggest that test materials loaded with different proportions of particular phonemes have different frequency importance functions. Comparison of the results with those from other studies suggests that importance functions depend to a degree on the available response options as well. PMID:3411027

  2. Finite-amplitude solitary states in viscoelastic shear flow: computation and mechanism

    NASA Astrophysics Data System (ADS)

    Kumar, K. Arun; Graham, Michael D.

    2001-09-01

    Starting from stationary bifurcations in Couette Dean flow, we compute stationary nontrivial solutions in the circular Couette geometry for an inertialess finitely extensible nonlinear elastic (FENE-P) dumbbell fluid. These solutions are isolated from the Couette flow branch arising at finite amplitude in saddle node bifurcations as the Weissenberg number increases. Spatially, they are strongly localized axisymmetric vortex pairs embedded in an arbitrarily long ‘far field’ of pure Couette flow, and are thus qualitatively, and to some extent quantitatively, similar to the ‘diwhirl’ (Groisman & Steinberg 1997) and ‘flame’ patterns (Baumert & Muller 1999) observed experimentally. For computationally accessible parameter values, these solutions appear only above the linear instability limit of the Couette base flow, in contrast to the experimental observations. Correspondingly, they are themselves linearly unstable. Nevertheless, extrapolation of the trend in the bifurcation points with increasing polymer extensibility suggests that for sufficiently high extensibility the diwhirls will come into existence before the linear instability, as seen experimentally.

  3. Reciprocal relations between perceived parental knowledge and adolescent substance use and delinquency: The moderating role of parent-teen relationship quality.

    PubMed

    Abar, Caitlin C; Jackson, Kristina M; Wood, Mark

    2014-09-01

    The current study prospectively examined hypothesized short- and long-term reciprocal relations between perceived parental knowledge and adolescent heavy episodic drinking, marijuana use, and delinquency. Using the contextual model of parenting style (Darling & Steinberg, 1993), we examined the extent to which the bidirectional nature of associations between knowledge and adolescent outcomes is dependent on a facet of parenting style: the quality of the parent-child relationship. Data came from the first 4 waves of the National Longitudinal Study of Youth 1997. The sample for the current study consisted of 5,419 students between 12 and 14 years of age at baseline (52% male) surveyed annually for 4 years. Parallel process, autoregressive latent trajectory models were used to examine relations between initial levels and change over time in perceived parental knowledge and adolescent risk, and short-term cross-lagged paths were included to examine bidirectionality while accounting for long-term associations. Results showed significant short-term and long-term bidirectionality between perceived parental knowledge and adolescent outcomes, with parent effects on students and student effects on parents. Long-term associations across constructs were negative, whereas short-term associations were positive. These reciprocal associations were shown to differ across levels of parent-child relationship quality with regard to adolescent heavy episodic drinking and delinquency, providing support for the contextual model of parenting style. Implications for future work on parent-child bidirectional relationships and parent-based interventions are discussed. PMID:25046124

  4. Empathy for Pain from Adolescence through Adulthood: An Event-Related Brain Potential Study

    PubMed Central

    Mella, Nathalie; Studer, Joseph; Gilet, Anne-Laure; Labouvie-Vief, Gisela

    2012-01-01

    Affective and cognitive empathy are traditionally differentiated, the affective component being concerned with resonating with another’s emotional state, whereas the cognitive component reflects regulation of the resulting distress and understanding of another’s mental states (see Decety and Jackson, 2004 for a review). Adolescence is a critical period for the development of cognitive control processes necessary to regulate affective processes: it is only in young adulthood that these control processes achieve maturity (Steinberg, 2005). Thus, one should expect adolescents to show greater automatic empathy than young adults. The present study aimed at exploring the neural correlates of affective (automatic) and cognitive empathy for pain from adolescence to young adulthood. With this aim, Event Related Potentials (ERPs) were recorded in 32 participants (aged 11–39) in a task designed to dissociate these components. ERPs results showed an early automatic fronto-central response to pain (that was not modulated by task demand) and a late parietal response to painful stimuli modulated by attention to pain cues. Adolescents exhibited earlier automatic responses to painful situations than young adults did and showed greater activity in the late cognitive component even when viewing neutral stimuli. Results are discussed in the context of the development of regulatory abilities during adolescence. PMID:23189065

  5. Integral group actions on symmetric spaces and discrete duality symmetries of supergravity theories

    SciTech Connect

    Carbone, Lisa; Murray, Scott H.; Sati, Hisham

    2015-10-15

    For G = G(ℝ), a split, simply connected, semisimple Lie group of rank n and K the maximal compact subgroup of G, we give a method for computing Iwasawa coordinates of K∖G using the Chevalley generators and the Steinberg presentation. When K∖G is a scalar coset for a supergravity theory in dimensions ≥3, we determine the action of the integral form G(ℤ) on K∖G. We give explicit results for the action of the discrete U-duality groups SL{sub 2}(ℤ) and E{sub 7}(ℤ) on the scalar cosets SO(2)∖SL{sub 2}(ℝ) and [SU(8)/( ± Id)]∖E{sub 7(+7)}(ℝ) for type IIB supergravity in ten dimensions and 11-dimensional supergravity reduced to D = 4 dimensions, respectively. For the former, we use this to determine the discrete U-duality transformations on the scalar sector in the Borel gauge and we describe the discrete symmetries of the dyonic charge lattice. We determine the spectrum-generating symmetry group for fundamental BPS solitons of type IIB supergravity in D = 10 dimensions at the classical level and we propose an analog of this symmetry at the quantum level. We indicate how our methods can be used to study the orbits of discrete U-duality groups in general.

  6. Influence of plasticity models upon the outcome of simulated hypervelocity impacts

    NASA Astrophysics Data System (ADS)

    Thomas, John N.

    1994-07-01

    This paper describes the results of numerical simulations of aluminum upon aluminum impacts which were performed with the CTH hydrocode to determine the effect plasticity formulations upon the final perforation size in the targets. The targets were 1 mm and 5 mm thick plates and the projectiles were 10 mm by 10 mm right circular cylinders. Both targets and projectiles were represented as 2024 aluminium alloy. The hydrocode simulations were run in a two-dimensional cylindrical geometry. Normal impacts at velocites between 5 and 15 km/s were simulated. Three isotropic yield stress models were explored in the simulations: an elastic-perfectly plastic model and the Johnson-Cook and Steinberg-Guinan-Lund viscoplastic models. The fracture behavior was modeled by a simple tensile pressure criterion. The simulations show that using the three strength models resulted in only minor differences in the final perforation diameter. The simulation results were used to construct an equation to predict the final hole size resulting from impacts on thin targets.

  7. Instrumented Taylor anvil-on-rod impact tests for validating applicability of standard strength models to transient deformation states

    NASA Astrophysics Data System (ADS)

    Eakins, D. E.; Thadhani, N. N.

    2006-10-01

    Instrumented Taylor anvil-on-rod impact tests have been conducted on oxygen-free electronic copper to validate the accuracy of current strength models for predicting transient states during dynamic deformation events. The experiments coupled the use of high-speed digital photography to record the transient deformation states and laser interferometry to monitor the sample back (free surface) velocity as a measure of the elastic/plastic wave propagation through the sample length. Numerical continuum dynamics simulations of the impact and plastic wave propagation employing the Johnson-Cook [Proceedings of the Seventh International Symposium on Ballistics, 1983, The Netherlands (Am. Def. Prep. Assoc. (ADPA)), pp. 541-547], Zerilli-Armstrong [J. Appl. Phys. C1, 1816 (1987)], and Steinberg-Guinan [J. Appl. Phys. 51, 1498 (1980)] constitutive equations were used to generate transient deformation profiles and the free surface velocity traces. While these simulations showed good correlation with the measured free surface velocity traces and the final deformed sample shape, varying degrees of deviations were observed between the photographed and calculated specimen profiles at intermediate deformation states. The results illustrate the usefulness of the instrumented Taylor anvil-on-rod impact technique for validating constitutive equations that can describe the path-dependent deformation response and can therefore predict the transient and final deformation states.

  8. Integral group actions on symmetric spaces and discrete duality symmetries of supergravity theories

    NASA Astrophysics Data System (ADS)

    Carbone, Lisa; Murray, Scott H.; Sati, Hisham

    2015-10-01

    For G = G(ℝ), a split, simply connected, semisimple Lie group of rank n and K the maximal compact subgroup of G, we give a method for computing Iwasawa coordinates of K∖G using the Chevalley generators and the Steinberg presentation. When K∖G is a scalar coset for a supergravity theory in dimensions ≥3, we determine the action of the integral form G(ℤ) on K∖G. We give explicit results for the action of the discrete U-duality groups SL2(ℤ) and E7(ℤ) on the scalar cosets SO(2)∖SL2(ℝ) and [SU(8)/{ ± Id}]∖E7(+7)(ℝ) for type IIB supergravity in ten dimensions and 11-dimensional supergravity reduced to D = 4 dimensions, respectively. For the former, we use this to determine the discrete U-duality transformations on the scalar sector in the Borel gauge and we describe the discrete symmetries of the dyonic charge lattice. We determine the spectrum-generating symmetry group for fundamental BPS solitons of type IIB supergravity in D = 10 dimensions at the classical level and we propose an analog of this symmetry at the quantum level. We indicate how our methods can be used to study the orbits of discrete U-duality groups in general.

  9. Modeling Hemispheric Detonation Experiments in 2-Dimensions

    SciTech Connect

    Howard, W M; Fried, L E; Vitello, P A; Druce, R L; Phillips, D; Lee, R; Mudge, S; Roeske, F

    2006-06-22

    Experiments have been performed with LX-17 (92.5% TATB and 7.5% Kel-F 800 binder) to study scaling of detonation waves using a dimensional scaling in a hemispherical divergent geometry. We model these experiments using an arbitrary Lagrange-Eulerian (ALE3D) hydrodynamics code, with reactive flow models based on the thermo-chemical code, Cheetah. The thermo-chemical code Cheetah provides a pressure-dependent kinetic rate law, along with an equation of state based on exponential-6 fluid potentials for individual detonation product species, calibrated to high pressures ({approx} few Mbars) and high temperatures (20000K). The parameters for these potentials are fit to a wide variety of experimental data, including shock, compression and sound speed data. For the un-reacted high explosive equation of state we use a modified Murnaghan form. We model the detonator (including the flyer plate) and initiation system in detail. The detonator is composed of LX-16, for which we use a program burn model. Steinberg-Guinan models5 are used for the metal components of the detonator. The booster and high explosive are LX-10 and LX-17, respectively. For both the LX-10 and LX-17, we use a pressure dependent rate law, coupled with a chemical equilibrium equation of state based on Cheetah. For LX-17, the kinetic model includes carbon clustering on the nanometer size scale.

  10. 2169 Steel Waveform Experiments

    NASA Astrophysics Data System (ADS)

    Furnish, M.; Alexander, C.; Reinhart, W.; Brown, J.

    2013-06-01

    In support of efforts to develop multiscale models of materials, we performed eight gas gun impact experiments on 2169 steel (21% Cr, 6% Ni, 9% Mn). These experiments provided shock, reshock and release velocimetry data, with initial shock stresses ranging from 10 to 50 GPa (particle velocities from 0.25 to 1.05 km/s). Both windowed and free-surface measurements were used, with samples 1 to 5 mm thick. The study focused on dynamic strength determination via the release/reshock paths. Reshock tests with explosively welded impactors produced clean results. The free-surface samples, which were steps on a single piece of steel, showed lower wavespeeds for thin (1 mm) samples than for thicker (2 or 4 mm) samples. A configuration used for the last three shots allowed release information to be determined from these free surface samples as well. The sample strength appears to increase with stress from ~1 GPa to ~3 GPa over this range, consistent with other recent work but about 40% above the Steinberg model. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  11. Decarburization of Levitated Fe-Cr-C Droplets by Carbon Dioxide

    NASA Astrophysics Data System (ADS)

    Wu, Paul; Yang, Yindong; Barati, Mansoor; McLean, Alex

    2014-12-01

    Experiments have been conducted at 1873 K (1600 °C) to study the kinetics of decarburization of Fe-Cr-C levitated droplets containing 10, 17, and 20 wt pct Cr using argon-carbon dioxide gas mixtures containing up to 30 pct CO2, at flow rates of 100, 1000, 3000 and 12200 mL min-1. It was found that chromium did not have a strong influence on the kinetics of decarburization while showing only minor effects on the extent of carbon removal. The results indicate that, for high carbon concentrations in the melt, the decarburization rates were controlled by mass transfer in the gas phase. Conventional formulation of governing mass transport numbers did not adequately describe the experimental observations made in this work. The observed rates are consistently higher than the values predicted using either the Ranz-Marshall correlation or the Steinberger-Treybal equation. A new correlation has been proposed to express the decarburization kinetics of levitated droplets for gas-flows in the range of Reynolds numbers between 2 and 100. The experimentally-derived model was found to be in excellent agreement with rate data derived from studies conducted by other researchers using levitated droplets.

  12. Joe L. Kincheloe: Genies and wishes: a review of Key Works in Critical Pedagogy

    NASA Astrophysics Data System (ADS)

    Ali-Khan, Carolyne; Siry, Christina

    2012-06-01

    We review Key Works in Critical Pedagogy: Joe L. Kincheloe edited by kecia hayes, Shirley R. Steinberg and Kenneth Tobin, which gathers the seminal works of Joe. L. Kincheloe and pairs them with contemporary scholars who respond to and push forward Kincheloe's work. The chapters of Key Works in Critical Pedagogy are arranged to begin with Kincheloe's earlier works, going back to 1991, and progress through to the last works he published before his death in 2008. Through this format, readers are able to see the evolution of Kincheloe's scholarship. In addition to this, a few key authors provide a behind the scenes look at the man who wrote the texts. As Kincheloe's ideas and the ideas of the scholars that he drew from are presented, applied, reworked and reconfigured, they shift and transform. The response chapters work to (in effect) show us the notes in the margins of scholars who have been influenced by Kincheloe's ideas. Using the metaphors of lamps and wish-granting genies, we argue that this book is an important tool in illuminating the way forward for social justice work, published in an historical moment that requires precisely this.

  13. Mesoscale Simulations of Power Compaction

    SciTech Connect

    Lomov, I; Fujino, D; Antoun, T; Liu, B

    2009-08-06

    Mesoscale 3D simulations of metal and ceramic powder compaction in shock waves have been performed with an Eulerian hydrocode GEODYN. The approach was validated by simulating shock compaction of porous well-characterized ductile metal using Steinberg material model. Results of the simulations with handbook values for parameters of solid 2024 aluminum have good agreement with experimental compaction curves and wave profiles. Brittle ceramic materials are not so well studied as metals, so material model for ceramic (tungsten carbide) has been fitted to shock compression experiments of non-porous samples and further calibrated to match experimental compaction curves. Direct simulations of gas gun experiments with ceramic powder have been performed and showed good agreement with experimental data. Numerical shock wave profile has same character and thickness as measured with VISAR. Numerical results show reshock states above the single-shock Hugoniot line also observed in experiments. They found that to receive good quantitative agreement with experiment it is essential to perform 3D simulations.

  14. Numerical Simulation of Interaction of Hypervelocity Particle Stream with a Target

    SciTech Connect

    Lomov, I; Liu, B; Georgevich, V; Antoun, T

    2007-07-31

    We present results of direct numerical simulations of impact of hypervelocity particle stream with a target. The stream of interest consists of submillimeter (30-300 micron) brittle ceramic particles. Current supercomputer capabilities make it possible to simulate a realistic size of streams (up to 20 mm in diameter and 500 mm in length) while resolving each particle individually. Such simulations make possible to study the damage of the target from synergistic effects of individual impacts. In our research we fixed the velocity distribution along the axis of the stream (1-4 km/s) and volume fraction of the solid material (1-10%) and study effects of particle size variation, particle and target material properties and surrounding air properties. We ran 3D calibration simulations with up to 10 million individual particles and conducted sensitivity studies with 2D cylindrically symmetric simulations. We used an Eulerian Godunov hydrocode with adaptive mesh refinement. The particles, target material and air are represented with volume-of-fluid approach. Brittle particle and target material has been simulated with pressure-dependent yield strength and Steinberg model has been used for metal targets. Simulations demonstrated penetration depth and a hole diameter similar to experimental observations and can explain the influence of parameters of the stream on the character of the penetration.

  15. Numerical Simulation of Interaction of Hypervelocity Particle Stream with a Target

    NASA Astrophysics Data System (ADS)

    Lomov, Ilya; Liu, Benjamin; Georgevich, Vlad; Antoun, Tarabay

    2007-12-01

    We present results of direct numerical simulations of impact of hypervelocity particle stream with a target. The stream of interest consists of submillimeter (30-300 micron) brittle ceramic particles. Current supercomputer capabilities make it possible to simulate a realistic size of streams (up to 20 mm in diameter and 500 mm in length) while resolving each particle individually. Such simulations make possible to study the damage of the target from synergistic effects of individual impacts. In our research we fixed the velocity distribution along the axis of the stream (1-4 km/s) and volume fraction of the solid material (1-10%) and study effects of particle size variation, particle and target material properties and surrounding air properties. We ran 3D calibration simulations with up to 10 million individual particles and conducted sensitivity studies with 2D cylindrically symmetric simulations. We used an Eulerian Godunov hydrocode with adaptive mesh refinement. The particles, target material and air are represented with volume-of-fluid approach. Brittle particle and target material has been simulated with pressure-dependent yield strength and Steinberg model has been used for metal targets. Simulations demonstrated penetration depth and a hole diameter similar to experimental observations and can explain the influence of parameters of the stream on the character of the penetration.

  16. Numerical simulation of interaction of hypervelocity particle stream with a target

    NASA Astrophysics Data System (ADS)

    Lomov, Ilya; Liu, Benjamin; Georgevich, Vlad; Antoun, Tarabay

    2007-06-01

    We present results of direct numerical simulations of impact of hypervelocity particle stream with a target. The stream of interest consists of submillimeter (30-300 micron) brittle ceramic particles. Current supercomputer capabilities make it possible to simulate a realistic size of streams (up to 20 mm in diameter and 500 mm in length) while resolving each particle individually. Such simulations make possible to study the damage of the target from synergistic effects of individual impacts. In our research we fixed the velocity distribution along the axis of the stream (1-4 km/s) and volume fraction of the solid material (1-10%) and study effects of particle size variation, particle and target material properties and surrounding air properties. We ran 3D calibration simulations with up to 10 million individual particles and conducted sensitivity studies with 2D cylindrically symmetric simulations. We used an Eulerian Godunov hydrocode with adaptive mesh refinement. The particles, target material and air are represented with volume-of-fluid approach. Brittle particle and target material has been simulated with pressure-dependent yield strength and Steinberg model has been used for metal targets. Simulations demonstrated penetration depth and a hole diameter similar to experimental observations and can explain the influence of parameters of the stream on the character of the penetration.

  17. Mesoscale simulations of powder compaction

    NASA Astrophysics Data System (ADS)

    Lomov, Ilya; Antoun, Tarabay; Liu, Benjamin

    2009-06-01

    Mesoscale 3D simulations of metal and ceramic powder compaction in shock waves have been performed with an Eulerian hydrocode GEODYN. The approach was validated by simulating shock compaction of porous well-characterized ductile metal using Steinberg material model. Results of the simulations with handbook values for parameters of solid 2024 aluminum have good agreement with experimental compaction curves and wave profiles. Brittle ceramic materials are not so well studied as metals, so material model for ceramic (tungsten carbide) has been fitted to shock compression experiments of non-porous samples and further calibrated to experimental match compaction curves. Direct simulations of gas gun experiments with ceramic powder have been performed and showed good agreement with experimental data. Numerical shock wave profile has same character and thickness as measured with VISAR. Numerical results show evidence of hard-to-explain reshock states above the single-shock Hugoniot line, which have also been observed in the experiments. We found that to receive good quantitative agreement with experiment it is essential to perform 3D simulations, since 2D results tend to underpredict stress levels for high-porosity powders regardless of material properties. We developed a process to extract macroscale information for the simulation which can be directly used in calibration of continuum model for heterogeneous media.

  18. ALE3D Model Predictions and Experimental Analysis of the Cookoff Response of Comp B*

    SciTech Connect

    Maienschein, J L; McClelland, M A; Wardell, J F; Reaugh, J E; Nichols, A L; Tran, T D

    2003-11-24

    ALE3D simulations are presented for the thermal explosion of Comp B (RDX,TNT) in a Scaled Thermal Explosion Experiment (STEX). Candidate models and numerical strategies are being tested using the ALE3D code which simulates the coupled thermal, mechanical, and chemical behavior during heating, ignition, and explosion. The mechanical behavior of the solid constituents is represented by a Steinberg-Guinan model while polynomial and gamma-law expressions are used for the equation of state of the solid and gas species, respectively. A gamma-law model is employed for the air in gaps, and a mixed material model is used for the interface between air and explosive. A three-step chemical kinetics model is used for each of the RDX and TNT reaction sequences during the heating and ignition phases, and a pressure-dependent deflagration model is employed during the rapid expansion. Parameters for the three-step kinetics model are specified using measurements of the One-Dimensional-Time-to-Explosion (ODTX), while measurements for burn rate are employed to determine parameters in the burn front model. We compare model predictions to measurements for temperature fields, ignition temperature, and tube wall strain during the heating, ignition, and explosive phases.

  19. [Genetic control of intercellular adhesion or how cadherins shape the fruitfly Drosophila melanogaster].

    PubMed

    Bécam, Isabelle; Huynh, Jean-René

    2007-03-01

    The beauty and diversity of cell shapes have always fascinated both biologists and physicists. In the early 1950, J. Holtfreter coined the term "tissue affinities" to describe the forces behind the spontaneous shaping of groups of cells. These tissue affinites were later on related to adhesive properties of cell membranes. In the 1960, Malcom Steinberg proposed the differential adhesion hypothesis (DAH) as a physical explanation of the liquid-like behaviour of tissues and cells during morphogenesis. However, the link between the cellular properties of adhesion molecules, such as the cadherins, and the physical rules that shape the body, has remained unclear. Recent in vitro studies have now shown that surface tensions, which drive the spontaneous liquid-like behaviour of cell rearrangements, are a direct and linear function of cadherin expression levels. Tissue surface tensions thus arise from differences in intercellular adhesiveness, which validates the DAH in vitro. The DAH was also vindicated in vivo by stunning experiments in Drosophila. The powerful genetic tools available in Drosophila allow to manipulate the levels and patterns of expression of several cadherins and to create artificially differences in intercellular adhesiveness. The results showed that simple laws of thermodynamics, as well as quantitative and qualitative differences in cadherins expression were sufficient to explain processes as complex as the establishment of the anterior-posterior axis and the formation of the compound eye in Drosophila. PMID:17349290

  20. Pubertal development and behavior: hormonal activation of social and motivational tendencies.

    PubMed

    Forbes, Erika E; Dahl, Ronald E

    2010-02-01

    Adolescence is a time of dramatic changes including rapid physical growth, the onset of sexual maturation, the activation of new drives and motivations, and a wide array of social and affective changes and challenges. This review focuses on behavioral changes in this interval and is organized by the claim that a key set of these adolescent changes are part of a more general re-orientation of social behavior. More specifically we hypothesize that pubertal maturation is associated with the activation of social and motivational tendencies, which in turn influence behavior and emotion in adolescence depending upon interactions with social context. We focus on evidence for two examples of these motivational changes: (1) increases in sensation-seeking (motivational tendency to want to experience high-intensity, exciting experiences) and (2) stronger natural interest in--and pursuit of--contact with peers and potential romantic partners. We consider how these motivational changes contribute to the broader social re-orientation of adolescence, including exploration of social experiences, development of skills and knowledge relevant to taking on adult social roles, individuation from family, and establishment of an individual identity, all of which represent core developmental tasks during this period in the life span (Blakemore, 2008; Dahl & Spear, 2004; Steinberg & Morris, 2000). The paper also emphasizes the importance of investigating and understanding the direct influences of puberty on behavior and disentangling these from the broader set of changes during adolescent development. PMID:19942334

  1. The intelligibility of words, sentences, and continuous discourse using the articulation index

    NASA Astrophysics Data System (ADS)

    Depaolis, R. A.

    1992-10-01

    The purpose of this research was to investigate the effect of message redundancy upon intelligibility. The original methodology for the Articulation Index (AI) French and Steinberg, J. Acoust. Soc. Am., 19, 90-119, 1947 was used to examine the relation between words, meaningful sentences, and continuous discourse (CD). One primary consideration was to derive the relations between the three speech types with tightly controlled, highly repeatable experimental conditions such that any difference between them could be attributed solely to inherent contextual differences. One male speaker recorded 616 monosyllabic words, 176 meaningful speech perception in noise (SPIN) sentences, and 44 seventh-grade reading level CD passages. Twenty-four normal hearing subjects made intelligibility estimates of the CD and sentences and identified words at each of 44 conditions of filtering and signal-to-noise ratio. The sentence intelligibility scores and continuous discourse intelligibility scores plotted versus the AI (transfer function) were within 0.05 AI of each other. The word recognition scores were considerably lower for equivalent AI values of both sentences and CD.

  2. Kilometer-scale, late Miocene and early Pliocene surface uplift in East Greenland: tectonic forerunners for the build-up of the Greenland Ice Sheet

    NASA Astrophysics Data System (ADS)

    Japsen, Peter; Green, Paul F.; Bonow, Johan M.

    2015-04-01

    anchoring points during the build-up of the Greenland Ice Sheet over the period leading up to the Pleistocene (Solgaard et al., 2013). Tectonic processes thus underpinned the build-up of the Greenland Ice Sheet (Steinberger et al., 2015). The three uplift phases in Greenland overlap in time with similar events in North America and Europe and correlate with changes in plate motion. The much higher elevation of East Greenland compared to West Greenland suggests active support in the east from the Iceland plume. These observations indicate a connection between mantle convection, changes in plate motion and vertical movements along passive continental margins. Bonow, J.M. et al. 2014. Global Planet. Change 116, 10-29. Japsen, P. et al. 2014. Global Planet. Change 116, 91-114. Molnar, P., England, P.C. 1990. Nature 346, 29-34. Solgaard, A.M. et al. 2013. Palaeogeography Palaeoclimatology Palaeoecology 392, 161-176. Steinberger, B. et al. 2015. Terra Nova in press.

  3. First-principles thermoelasticity of transition metals at high pressure I. Tantalum prototype in the quasi-harmonic limit

    SciTech Connect

    Orlikowski, D; Soderlind, P; Moriarty, J A

    2006-04-25

    The thermoelastic properties of bcc tantalum have been investigated over a broad range of pressures (up to 10 Mbar) and temperatures (up to 26,000 K) using a new first-principles approach that accurately accounts for cold, electron-thermal, and ion-thermal contributions in materials where anharmonic effects are small. Specifically, we have combined ab initio full-potential linear-muffin-tin-orbital (FP-LMTO) electronic-structure calculations for the cold and electron-thermal contributions to the elastic moduli with phonon contributions for the ion-thermal part calculated using model generalized pseudopotential theory (MGPT). For the latter, a summation of terms over the Brillouin zone is performed within the quasi-harmonic approximation, where each term is composed of a strain derivative of the phonon frequency at a particular k point. At ambient pressure, the resulting temperature dependence of the Ta elastic moduli is in excellent agreement with ultrasonic measurements. The experimentally observed anomalous behavior of C{sub 44} at low temperatures is shown to originate from the electron-thermal contribution. At higher temperatures, the main contribution to the temperature dependence of the elastic moduli comes from thermal expansion, but inclusion of the electron- and ion-thermal contributions is essential to obtain quantitative agreement with experiment. In addition, the pressure dependence of the moduli at ambient temperature compares well with recent diamond-anvil cell measurements to 1.05 Mbar. Moreover, the calculated longitudinal and bulk sound velocities in polycrystalline Ta at higher pressure and temperature in the vicinity of shock melting ({approx} 3 Mbar) agree well with data obtained from shock experiments. However, at high temperatures along the melt curve above 1 Mbar, the B{prime} shear modulus becomes negative indicating the onset of unexpectedly strong anharmonic effects. Finally, the assumed temperature dependence of the Steinberg

  4. Effects of DIDS on the chick retinal pigment epithelium. I. Membrane potentials, apparent resistances, and mechanisms.

    PubMed

    Gallemore, R P; Steinberg, R H

    1989-06-01

    While little is known about the transport properties of the retinal pigment epithelium (RPE) basal membrane, mechanisms for anion movement across the basal membrane appear to be present (Miller and Steinberg, 1977; Hughes et al., 1984; Miller and Farber, 1984). This work examines the electrophysiological effects of the anion conductance blocker, 4,4'-diisothiocyanostilbene-2,2'-disulfonate (DIDS) on the basal membrane of an in vitro preparation of chick retina-RPE-choroid. DIDS (10-125 microM), added to the choroidal bath, decreased the transtissue potential by decreasing the potential across the RPE. Intracellular RPE recordings showed that DIDS affected the membrane potential in 2 phases, initially hyperpolarizing the basal membrane and then, after prolonged exposure, depolarizing the apical membrane. Resistance assessment by transtissue current pulses and intracellular c-wave recordings suggested that DIDS increased basal membrane resistance (Rba) during the first phase and increased apical membrane resistance (Rap) during the second phase. Measurements of intracellular Cl- activity (aiCl) showed that Cl- was actively accumulated by the chick RPE since it was distributed above equilibrium across both the apical and basal membranes. Perfusion of the basal membrane with 50 microM DIDS significantly increased aiCl-. The DIDS-induced basal membrane hyperpolarization, apparent increase in Rba, and increase in aiCl- are all consistent with Cl- -conductance blockade. During the second phase, apical membrane responsiveness to the light-evoked decrease in subretinal [K+]o (Oakley, 1977) was reduced an average of 58%. This finding, given the second-phase apical membrane depolarization and apparent increase in Rap, is consistent with a decrease in apical membrane K+ conductance.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2723761

  5. 2169 steel waveform experiments.

    SciTech Connect

    Furnish, Michael David; Alexander, C. Scott; Reinhart, William Dodd; Brown, Justin L.

    2012-11-01

    In support of LLNL efforts to develop multiscale models of a variety of materials, we have performed a set of eight gas gun impact experiments on 2169 steel (21% Cr, 6% Ni, 9% Mn, balance predominantly Fe). These experiments provided carefully controlled shock, reshock and release velocimetry data, with initial shock stresses ranging from 10 to 50 GPa (particle velocities from 0.25 to 1.05 km/s). Both windowed and free-surface measurements were included in this experiment set to increase the utility of the data set, as were samples ranging in thickness from 1 to 5 mm. Target physical phenomena included the elastic/plastic transition (Hugoniot elastic limit), the Hugoniot, any phase transition phenomena, and the release path (windowed and free-surface). The Hugoniot was found to be nearly linear, with no indications of the Fe - phase transition. Releases were non-hysteretic, and relatively consistent between 3- and 5-mm-thick samples (the 3 mm samples giving slightly lower wavespeeds on release). Reshock tests with explosively welded impactors produced clean results; those with glue bonds showed transient releases prior to the arrival of the reshock, reducing their usefulness for deriving strength information. The free-surface samples, which were steps on a single piece of steel, showed lower wavespeeds for thin (1 mm) samples than for thicker (2 or 4 mm) samples. A configuration used for the last three shots allows release information to be determined from these free surface samples. The sample strength appears to increase with stress from ~1 GPa to ~ 3 GPa over this range, consistent with other recent work but about 40% above the Steinberg model.

  6. Reassembling the Ontong Java-Manihiki-Hikurangi large igneous province: Insights and challenges

    NASA Astrophysics Data System (ADS)

    Chandler, M. T.; Wessel, P.; Taylor, B.; Sager, W. W.

    2012-12-01

    The tectonic history of ~30% of the Pacific plate south of Equator which formed during the Cretaceous Normal Supercron is difficult to establish due to its lack of a lineated magnetic anomaly pattern. This region, including the Ontong Java, Manihiki, and Hikurangi large igneous provinces, as well as the interlying Ellice Basin and Osbourn Trough, lacks active seafloor spreading centers and has thus been largely neglected by seagoing research scientists. Nonetheless, the CNS South Pacific may prove to be important for understanding Pacific history. Ontong Java's mean basement paleolatitude measurement differs from absolute plate model (APM) reconstructions for the plateau by ~8--19 degrees (Chandler et al. (2012)), indicating that either current APM models are erroneous, substantial plume drift or true polar wander occurred, or that Ontong Java experienced unrecognized motion early in its history. In support of the latter are recent findings that little to no Louisville plume drift occurred after ~70 Ma (Gee et al. (2011)), that true polar wander estimates for the ~125 Ma Ontong Java vicinity are negligible (Steinberger and Torsvik (2008)), and our recent observation of a 2:1 bias between Ontong Java's paleolatitude and latitude differences (Chandler and Wessel (2011), Chandler et al. (In prep)). These differences, computed among ODP Sites 807 and 1183 - 1187, suggest significant clockwise rotation of ~40 degrees since Ontong Java's formation at ~125 Ma. Although this rotation does not resolve the paleolatitude discrepancy it does suggest that Ontong Java's paleolatitudes may not be suitable for constraining Pacific APM. Seafloor formed at the Osbourn Trough and in the Ellice Basin make up much of the CNS South Pacific. These regions exhibit fossil spreading centers believed responsible for the breakup of Earth's largest known igneous province, the Ontong Java-Manihiki-Hikurangi super-plateau (e.g., Taylor (2006), Chandler et al. (2012)). Understanding this little

  7. Responses of coastal ecosystems to environmental variability in emerging countries from the Americas

    NASA Astrophysics Data System (ADS)

    Muniz, Pablo; Calliari, Danilo; Giménez, Luis; Defeo, Omar

    2015-12-01

    Coastal ecosystems supply critical ecological services and benefits to human society (Barbier et al., 2011). Nearly 38% of the global monetary value of annual ecosystem services arises from estuaries, seagrass and algal beds, coral reefs and shelf ecosystems (Costanza et al., 1997). However, these ecosystems are being increasingly affected by multiple drivers acting simultaneously at several spatial and temporal scales (Lotze et al., 2006; Hoegh-Guldberg and Bruno, 2010). Climate change (temperature increase, sea level rise, ocean acidification), human activities (e.g. land use/cover change, pollution, overexploitation, translocation of species), and extreme natural events (storms, floods, droughts) are the most important drivers degrading the resilience of coastal systems. Such factors operate on individual level processes, leading organisms away from their niches (Steinberg, 2013) or modifying rates and phenology (Giménez, 2011; Mackas et al., 2012, Deutsch et al., 2015). All of these influence ecosystem level processes, causing changes in species composition, diversity losses and deterioration of ecosystem functions (Worm et al., 2006; Defeo et al., 2009; Doney et al., 2011; Dornelas et al., 2014). The rate of change in habitats, species distributions and whole ecosystems has accelerated over the past decades as shown, for example, in the increase in the frequency of events of coastal hypoxia (Diaz and Rosenberg, 2008,Vaquer-Sunyer and Duarte, 2008), extensive translocation of species by global shipping (Seebens et al., 2013), and in ecosystem regime shifts (Möllmann et al., 2015 and references therein). Some coastal areas have been transformed into novel ecosystems with physical and biological characteristics outside their natural range of variability (Cloern et al., 2015) while others are likely to become sink areas, limiting the migration of marine species away from warming habitats (Burrows et al., 2014).

  8. Biomineral formation as a biosignature for microbial activities Precambrian cherts

    NASA Astrophysics Data System (ADS)

    Rincón Tomás, Blanca; Mühlen, Dominik; Hoppert, Michael; Reitner, Joachim

    2015-04-01

    In recent anoxic sediments manganese(II)carbonate minerals (e.g., rhodochrosite, kutnohorite) derive mainly from the reduction of manganese(IV) compounds by microbial anaerobic respiration. Small particles of rhodochrosite in stromatolite-like features in the Dresser chert Fm (Pilbara supergroup, W-Australia), associated with small flakes of kerogen, account for biogenic formation of the mineral in this early Archaean setting. Contrastingly, the formation of huge manganese-rich (carbonate) deposits requires effective manganese redox cycling, also conducted by various microbial processes, mainly requiring conditions of the early and late Proterozoic (Kirschvink et al., 2000; Nealson and Saffrani 1994). However, putative anaerobic pathways like microbial nitrate-dependent manganese oxidation (Hulth et al., 1999), anoxygenic photosynthesis (Johnson et al., 2013) and oxidation in UV light may facilitate manganese cycling even in a reducing atmosphere. Thus manganese redox cycling might have been possible even before the onset of oxygenic photosynthesis. Hence, there are several ways how manganese carbonates could have been formed biogenically and deposited in Precambrian sediments. Thus, the minerals may be suitable biosignatures for microbial redox processes in many respects. The hyperthermophilic archaeon Pyrobaculum islandicum produces rhodochrosite during growth on hydrogen and organic compounds and may be a putative model organism for the reduction of Mn(IV). References Hulth S, Aller RC, Gilbert F. (1999) Geochim Cosmochim Acta, 63, 49-66. Johnson JE, Webb SM, Thomas K, Ono S, Kirschvink JL, Fischer WW. (2013) Proc Natl Acad Sci USA, 110, 11238-11243. Kirschvink JL, Gaidos EJ, Bertani LE, Beukes NJ, Gutzmer J, Maepa LN, Steinberger LE. (2000) Proc Natl Acad Sci USA, 97, 1400-1405. Nealson KH, Saffarini D. (1994). Annu Rev Microbiol, 48, 311-343.

  9. Outcome after tantalum rod implantation for treatment of femoral head osteonecrosis

    PubMed Central

    Varitimidis, Sokratis E; Dimitroulias, Apostolos P; Karachalios, Theophilos S; Dailiana, Zoe H

    2009-01-01

    Background and purpose Tantalum rod implantation has recently been proposed for treatment of early stages of femoral head osteonecrosis. The purpose of our study was to report the early results of its use in pre- and post-collapse stages of the disease. Methods We studied prospectively 27 patients who underwent tantalum rod implantation for treatment of nontraumatic femoral head osteonecrosis between December 2000 and September 2005. Patients were evaluated radiologically and clinically using the Steinberg classification and the Harris hip score (HHS). Disease stage varied between stages II and IV. Mean follow-up time was 38 (15–71) months. Results 1 patient (1 hip) died 15 months after surgery for reasons unrelated to it. 13 of 26 hips remained at the same radiographic stage, and 13 deteriorated. Mean HHS improved from 49 to 85. 6 patients required conversion to total hip arthroplasty. When the procedure was used for stages III and IV, both radiological outcome and revision rates were worse than for the stage II hips. There was, however, no difference in postoperative HHS between patients at pre- and post-collapse stages at the time of initial evaluation. Survivorship, with revision to THA as the endpoint, was 70% at 6 years. Interpretation The disease process does not appear to be interrupted, but there was a significant improvement in hip function initially in most hips. Tantalum rod implantation is a safe “buy-time” technique, especially when other joint salvage procedures are not an option. Appropriate patient selection and careful rod insertion are needed for favorable results. PMID:19297785

  10. Clinical Results of Auto-Iliac Cancellous Bone Grafts Combined with Implantation of Autologous Bone Marrow Cells for Osteonecrosis of the Femoral Head: A Minimum 5-Year Follow-Up

    PubMed Central

    Kang, Joon Soon; Moon, Kyoung Ho; Kim, Bom-Soo; Shin, Sang Hyun; Shin, Byung Ki; Ryu, Dong-Jin

    2013-01-01

    Purpose There are no reports about bone graft and cell therapy for the osteonecrosis of femoral head (ONFH). We prospectively evaluated the clinical results of auto-iliac cancellous bone grafts combined with implantation of autologous bone marrow cells for ONFH. Materials and Methods Sixty-one hips in 52 patients with ONFH treated with bone graft and cell therapy were enrolled, and the average follow-up of the patients was 68 (60-88) months. Necrotic lesions were classified according to their size by the Steinberg method and location of necrosis. Results At the last follow-up, the percentage of excellent or good results was 80% (12/15 hips) in the small lesion group, 65% (17/26 hips) in the medium size group, and 28% (6/20 hips) in the large size group. The procedures were a clinical success in 4 of 5 hips (80%) of stage I, 23 of 35 hips (65.7%) of stage II, 7 of 18 hips (38.9%) of stage III, and 1 of 3 hips (33.3%) of stage IV grade, according to the Association Research Circulation Osseous grading system. Among the 20 cases with large sized necrotic lesions, 17 cases were laterally located and this group showed the worst outcomes, with 13 hips (76.5%) having bad or failed clinical results. Conclusion The results of the present study suggested that patients who have a large sized lesion or medium sized laterally located lesion would not be good candidates for the head preserving procedure. However, for medium sized lesions, this procedure generated clinical results comparable to those of other head preserving procedures. PMID:23364989

  11. A model for shape generation by strain and cell-cell adhesion in the epithelium of an arthropod leg segment.

    PubMed

    Mittenthal, J E; Mazo, R M

    1983-02-01

    We present a model for the energetic factors determining the most stable shape of a tubular epithelium such as the hypodermis of an arthropod leg segment. The model uses the analysis by Steinberg (1963) of rearrangement of cells in aggregates under the influence of differential adhesion, combining this analysis with the assumption that the epithelium behaves as an elastic sheet. The epithelium is assumed to consist of blocks of cells with different adhesive affinities, which remain unmixed in a quilt pattern. Rearrangement of cells within each block can adjust the shape of the tube by changing the shapes of the blocks. By means of such rearrangements the tube develops that shape which minimizes a free energy. The free energy is the difference between the energy of mechanical strain due to bending of the epithelium and the work of adhesion among cells. Minimization of the free energy for a cylindrical segment yields a scaling relation involving the length and radius of the segment. Leg segments of Drosophila conformed approximately to this relation, with deviations which suggest that a whole-limb pattern of adhesive affinities modulates the shaping effects of an adhesive pattern repeated in each leg segment. The model also predicts a transient deformation in an epithelium following a grafting operation. For example, deleting a slab of tissue from a tubular segment and reuniting the cut ends should produce a constriction of the tube at the host-graft junction. We propose that patterns of strain and adhesion can provide positional information which regulates subsequent development. Local increases in strain or adhesive disparity may stimulate mitoses; the resulting changes in distribution of cells will affect morphogenesis. PMID:6834865

  12. Patterns and Predictors of Mother-Adolescent Discrepancies across Family Constructs.

    PubMed

    Rote, Wendy M; Smetana, Judith G

    2016-10-01

    Parent-child discrepancies pervade the family literature; they appear in reports of relationship dynamics (e.g., conflict; Laursen et al. 1998), parent and child behaviors (e.g., monitoring; De Los Reyes et al. 2010), and individual family members' beliefs (e.g., parental legitimate authority; Smetana 2011). Discrepancies are developmentally normative (Steinberg 2001) but also may be indicators of relationship and adjustment problems for teens (Ohannessian 2012). Because of this variation, it is important to consider the extent to which parent-child discrepancies are a function of both the dyad and the family construct considered. The present study contributed to our understanding of informant discrepancies in family relationships by considering the patterning, consistency, and correlates of mother-adolescent discrepancies across three family constructs that vary in their objectivity. Using person-centered analyses, discrepancies in adolescents' and mothers' ratings of parents' right to know about teens' activities, mothers' knowledge of them, and positive mother-adolescents relationships were examined in 167 middle class, primarily European American mother-adolescent dyads (M teen age = 15.68 years, SD = .64, 53 % female). Each construct was best described by three profiles, one where adolescents' standardized ratings were consistently higher than mothers', one showing the reverse, and one revealing little disagreement. Adolescent-reported problem behavior (but not depression), behavioral and psychological control, and mothers' wellbeing significantly predicted profile membership. Most dyads maintained consistent membership in a discrepancy profile across at least two family constructs. Results contribute to understanding the different sources of discrepancies in views of the family. PMID:27295041

  13. Immunoglobulin (GM and KM) allotypes and relation to population history in native peoples of British Columbia: Haida and Bella Coola.

    PubMed

    Field, L L; Gofton, J P; Kinsella, T D

    1988-06-01

    Differences in the frequencies of GM haplotypes among native peoples of the Americas support the hypothesis that there were three distinct waves of migration from northeast Asia into the Americas: Paleo-Indian, Na-Dene, and Inuit (Eskimo)-Aleut (Salzano and Steinberg: Am. J. Hum. Genet. 17:273-279, 1965; Sukernik and Osipova: Hum. Genet. 61:148-153, 1982; Williams et al.:Am. J. Phys. Anthropol. 66:1-19, 1985; Szathmary: In R Kirk and E Szathmary (eds): Out of Asia: Peopling of the Americas and the Pacific. Canberra: The Journal of Pacific History, Canberra Australian National University, pp. 79-104, 1985). We studied GM allotypes in two linguistically unique populations of Canadian west coast native peoples, the Haida and the Bella Coola, and compared them to GM frequencies in populations that are supposed descendants of the three migrations, in order to investigate the possible genetic relationships of these British Columbia (BC) groups to other native populations. We also estimated the amount of European admixture from the frequency of the Caucasian haplotype, Gm3;5. Results showed that the frequencies in both BC populations of the three common native haplotypes (Gm1,17;21, Gm1,2,17;21, and Gm1,17;15,16), were intermediate between the frequencies in supposed descendants of Paleo-Indian and Na-Dene. These genetic findings are consistent with the controversial hypothesis of archeologist C. Borden (Science 203:963-971, 1979) that, following deglaciation about 13,000 years ago, British Columbia was repopulated by peoples from the north (?Na-Dene) and by culturally distinct peoples from the south (?Paleo-Indian). Caucasian admixture estimates suggested that the Haida and Bella Coola have also experienced moderate amounts (12-20%) of genetic input from European-originating peoples.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3414788

  14. Binary-YORP Coefficients for Known Asteroid Shapes

    NASA Astrophysics Data System (ADS)

    McMahon, Jay W.; Scheeres, D. J.

    2012-10-01

    The binary YORP (bYORP) effect has been hypothesized to be a significant factor in the evolution of near-Earth binary asteroid systems (Cuk and Burns, Icarus, v.176, pp.418-431, 2005; McMahon and Scheeres, CMDA, v.106, pp.261-300, 2010). However, understanding of the coefficient values for realistic asteroid shapes is lacking due to the small number of shape models available for the generally smaller secondary asteroids. Until now, we have only calculated the coefficients based on the shape of 1999 KW4 Beta, although various studies by other authors have computed coefficients for artificially generated asteroids based on Gaussian Spheres and some shape models without self-shadowing (Steinberg and Sari, The Astronomical Journal, v.141, pp.55-64, 2011). We also scaled the 1999 KW4 Beta coefficients to other binary systems with no knowledge of the other systems' secondary shapes in order to make evolutionary predictions (McMahon and Scheeres, Icarus Vol. 209, pp 494-509, 2010). In this study, we compute the bYORP coefficient for a range of asteroid shapes, using these as a stand-in for actual secondaries. This allows us to circumvent the lack of information on binary asteroid secondaries and to develop a richer database of realistic coefficients. While this approach may miss some key features of binary secondaries, at the least it provides some statistics on the expected variability of the bYORP coefficient. We analyze all available asteroid shape models on the PDS-SBN, including radar-based shape models and models estimated from past spacecraft missions. The coefficients are computed with an updated algorithm that includes the effects of self-shadowing. We also present the coefficients for perturbed versions of the available shape models, which give effective error bars to the computed coefficients due to inexact shape models. Finally, we discuss the dynamical implications of the derived bYORP coefficients on binary asteroid evolution.

  15. The eustatic chimera: isn't the Cenomanian maximum flood a dynamic topography puzzle?

    NASA Astrophysics Data System (ADS)

    Ostanciaux, E.; Robin, C.; Guillocheau, F.; Trotin, G.; Husson, L.

    2012-04-01

    More and more, dynamic topography is predicted to seriously control sea level, which challenges the concept of eustasy, but field evidence are sparse. In order to evaluate the space and time evolution of relative sea level variations, we made paleogeographic reconstructions for three consecutive stages around the presumed Cenomanian maximum flood. For that purpose, we compiled stratigraphic charts and existing paleogeographic maps to reconstruct shorelines at a global scale and infer transgressive and regressive phases. The Cenomanian transgressive phase is essentially present around the Tethys, whereas regression prevails at higher latitudes. Furthermore, diachronicity accompanies the presumed sea level high, for the trend reverses between the three stages in the northern hemisphere while it further subsides in the southern one. These reconstructions therefore suggest that an evolving degree two structure of uplift and subsidence may be more endemic of this period than uniform sea level change and thus, they better recall internal dynamics than eustasy. Indeed, flooding accompanies the Tethyan subduction zone, while regressions are located above spreading oceans. We interpret relative sea level change during the late Cretaceous as the traces of the negative dynamic subsidence above the Tehyan slab in the one hand, and in the other hand of the superplumes (African in particular) that lead to the breakup of the Atlantic. We further confront our results to the predictions of Steinberger, who provides estimates of dynamic topography since the latest Albian. We conformably observe, for instance, positive anomalies in North America, in the Baltic area, or in South Africa, but the model mostly fails to predict the observe diachronicity in vertical ground motion.

  16. The stratification and cyclicity of the Dachstein Limestone in Lofer, Leogang and Steinernes Meer (Northern Calcareous Alps, Austria)

    NASA Astrophysics Data System (ADS)

    Schwarzacher, W.

    2005-11-01

    The Dachstein Limestone of the Northern Calcareous Alps contains massive limestone beds, capped by dolomitic horizons. Groups of beds form bundles or stratification cycles and spectral analysis gives evidence of at least 3 orders of cycle frequencies. The regularity in the repetition of the limestones and dolomites was first pointed out by Sander (1936) [Sander, B., 1936. Beitrage zur Kenntniss der Anlagerungsgefuege. Mineral. Petrogr. Mitt. 48, 27-139] and the repetition of definite groups by Schwarzacher (1948, 1954) [Schwarzacher, W., 1948. Ueber die sedimentaere Rhytmik des Dachstein Kalkes von Lofer. Verh. Geol. Bundesanst. 1947 (Heft 10-12), 176-188; Schwarzacher, W., 1954. Ueber die Grossrhytmik des Dachstein Kalkes von Lofer. Tschermaks Mineral. Petrogr. Mitt. 4, 44-54]. The facies associated with the change from limestone to dolomite was interpreted by Fischer (1964) [Fischer, A.G., 1964. The Lofer cyclothems of the alpine Triassic. In: Merriam, D.F. (Ed), Symposium on Cyclic Sedimentation. Kansas Geological Survey Bull. 169, 107-146] as an environmental change from lagoonal to peritidal and consequently as evidence of rising and falling sea level. The present paper is based on the study of over 500 aerial photographs from the Loferer and Leoganger Steinberge and also on a detailed section, measured by Paul Enos and E. Samankassou in the Steinernes Meer. It was found that the Dachstein Limestone from Lofer and Leogang comprised about 35 stratification cycles of approximately 20 m thickness. This may correspond to a similar number of cycles in the Steinernes Meer where the spectral analysis gave a cycle thickness of 27 m and 13.6 m. The interpretation of the bundle as being caused by the 100 ka eccentricity cycle is considered tenable.

  17. Modified surgical techniques of free vascularized fibular grafting for treatment of the osteonecrosis of femoral head: results from a series of 407 cases.

    PubMed

    Gao, You-Shui; Chen, Sheng-Bao; Jin, Dong-Xu; Sheng, Jia-Gen; Cheng, Xiang-Guo; Zhang, Chang-Qing

    2013-11-01

    The goal for treatment of osteonecrosis of the femoral head (ONFH) is to relieve pain, preserve the contour of the femoral head, and delay the need for total hip arthroplasty. The free vascularized fibular grafting (FVFG) has been shown to support the subchondral architecture as well as restore local circulation for the necrotic femoral head in treatment of ONFH. This report aimed to present the clinical results of the use of a modified surgical technique of FVFG for treatment of ONFH. Four hundred and seven patients with 578 hips of ONFH were included. The patients' average age was 36.7 years old (ranging 19-55 years old). The disease was staged from II to V based on the Steinberg classification system. By the modified procedure, the vascularized fibular graft was harvested via a lateral incision with fibular osteotomy prior to the exposure of the vascular pedicle, and the removal of necrotic tissue and inset of graft were performed through an anterior approach. The operative time averaged 90 min for unilateral ONFH (ranging 75-110 min) and 190 min for simultaneous treatment of bilateral ONFH (ranging 160-230 min). The average length of follow-up was 5.0 years (ranging 3-10 years). The complications included one infection in one case, temporary loss of sensation of the thigh in eleven cases, and restricted motion of the great toe in nine cases. The Harris hip score of patients improved from 65.0 to 86.9 on average. Radiographic evaluation showed no changes in 331 hips (57.3%), improvement in 195 hips (33.7%) and necrosis progression in 52 hips (9.0%). Twenty-three hips (4.0%) in 20 patients had total hip arthroplasty during the period. These results show that the modified technique of the use of FVFG for treatment of ONFH yields similar postoperative results in comparison to the traditional method. PMID:23907776

  18. CTH: A software family for multi-dimensional shock physics analysis

    SciTech Connect

    Hertel, E.S. Jr.; Bell, R.L.; Elrick, M.G.; Farnsworth, A.V.; Kerley, G.I.; McGlaun, J.M.; Petney, S.V.; Silling, S.A.; Taylor, P.A.; Yarrington, L.

    1992-12-31

    CTH is a family of codes developed at Sandia National Laboratories for modeling complex multi-dimensional, multi-material problems that are characterized by large deformations and/or strong shocks. A two-step, second-order accurate Eulerian solution algorithm is used to solve the mass, momentum, and energy conservation equations. CTH includes models for material strength, fracture, porous materials, and high explosive detonation and initiation. Viscoplastic or rate-dependent models of material strength have been added recently. The formulations of Johnson-Cook, Zerilli-Armstrong, and Steinberg-Guinan-Lund are standard options within CTH. These models rely on using an internal state variable to account for the history dependence of material response. The implementation of internal state variable models will be discussed and several sample calculations will be presented. Comparison with experimental data will be made among the various material strength models. The advancements made in modelling material response have significantly improved the ability of CTH to model complex large-deformation, plastic-flow dominated phenomena. Detonation of energetic material under shock loading conditions has been of great interest. A recently developed model of reactive burn for high explosives (HE) has been added to CTH. This model along with newly developed tabular equations-of-state for the HE reaction by-products has been compared to one- and two-dimensional explosive detonation experiments. These comparisons indicate excellent agreement of CTH predictions with experimental results. The new reactive burn model coupled with the advances in equation-of-state modeling make it possible to predict multi-dimensional burn phenomena without modifying the model parameters for different dimensionality. Examples of the features of CTH will be given. The emphasis in simulations shown will be in comparison with well characterized experiments covering key phenomena of shock physics.

  19. Elastic turbulence in curvilinear flows of polymer solutions

    NASA Astrophysics Data System (ADS)

    Groisman, Alexander; Steinberg, Victor

    2004-03-01

    Following our first report (A Groisman and V Steinberg 2000 Nature 405 53), we present an extended account of experimental observations of elasticity-induced turbulence in three different systems: a swirling flow between two plates, a Couette-Taylor (CT) flow between two cylinders, and a flow in a curvilinear channel (Dean flow). All three set-ups had a high ratio of the width of the region available for flow to the radius of curvature of the streamlines. The experiments were carried out with dilute solutions of high-molecular-weight polyacrylamide in concentrated sugar syrups. High polymer relaxation time and solution viscosity ensured prevalence of non-linear elastic effects over inertial non-linearity, and development of purely elastic instabilities at low Reynolds number (Re) in all three flows. Above the elastic instability threshold, flows in all three systems exhibit features of developed turbulence. They include: (i) randomly fluctuating fluid motion excited in a broad range of spatial and temporal scales and (ii) significant increase in the rates of momentum and mass transfer (compared with those expected for a steady flow with a smooth velocity profile). Phenomenology, driving mechanisms and parameter dependence of the elastic turbulence are compared with those of the conventional high-Re hydrodynamic turbulence in Newtonian fluids. Some similarities as well as multiple principal differences were found. In two out of three systems (swirling flow between two plates and flow in the curvilinear channel), power spectra of velocity fluctuations decayed rather quickly, following power laws with exponents of about -3.5. It suggests that, being random in time, the flow is rather smooth in space, in the sense that the main contribution to deformation and mixing (and, possibly, elastic energy) is coming from flow at the largest scale of the system. This situation, random in time and smooth in space, is analogous to flows at small scales (below the Kolmogorov

  20. Dissociative amnesia in dissociative disorders and borderline personality disorder: self-rating assessment in a college population.

    PubMed

    Sar, Vedat; Alioğlu, Firdevs; Akyuz, Gamze; Karabulut, Sercan

    2014-01-01

    Dissociative amnesia (DA) among subjects with a dissociative disorder and/or borderline personality disorder (BPD) recruited from a nonclinical population was examined. The Steinberg Dissociative Amnesia Questionnaire (SDAQ), the Childhood Trauma Questionnaire, and the self-report screening tool of the BPD section of the Structured Clinical Interview for DSM-IV(SCID-BPD) were administered to 1,301 college students. A total of 80 participants who were diagnosed with BPD according to the clinician-administered SCID-BPD and 111 nonborderline controls were evaluated using the Structured Clinical Interview for DSM-IV Dissociative Disorders (SCID-D) by a psychiatrist blind to diagnosis and scale scores. Internal consistency analyses and test-retest evaluations suggested that the SDAQ is a reliable instrument for the population studied. Of the participants, 20.6% reported an SDAQ score of 20 or above and impairment by DA. Those who had both dissociative disorder and BPD (n = 78) had the highest SDAQ scores. Both disorders had significant effects on the SCID-D total and amnesia scores in the variance analysis. On SDAQ scores, however, only BPD had this effect. There was a significant interaction between the 2 disorders for the SCID-D total but not for the SDAQ or SCID-D amnesia scores. BPD represented the severity of dissociation and childhood trauma in this study group. However, in contrast to the dissociative disorders, BPD was characterized by better awareness of DA in self-report. The discrepancies between self-report and clinical interview associated with BPD and dissociative disorders are discussed in the context of betrayal theory (J. J. Freyd, 1994) of BPD and perceptual theory (D. B. Beere, 2009) of dissociative disorders. PMID:24678926

  1. Ignition and combustion of bulk metals under elevated, normal and reduced gravity conditions

    NASA Technical Reports Server (NTRS)

    Abbud-Madrid, Angel; Branch, Melvyn C.; Daily, John W.

    1995-01-01

    This research effort is aimed at providing further insight into this multi-variable dependent phenomena by looking at the effects of gravity on the ignition and combustion behavior of metals. Since spacecraft are subjected to higher-than-1g gravity loads during launch and reentry and to zero-gravity environments while in orbit, the study of ignition and combustion of bulk metals at different gravitational potentials is of great practical concern. From the scientific standpoint, studies conducted under microgravity conditions provide simplified boundary conditions since buoyancy is removed, and make possible the identification of fundamental ignition mechanisms. The effect of microgravity on the combustion of bulk metals has been investigated by Steinberg, et al. on a drop tower simulator. However, no detailed quantitative work has been done on ignition phenomena of bulk metals at lower or higher-than-normal gravitational fields or on the combustion characteristics of metals at elevated gravity. The primary objective of this investigation is the development of an experimental system capable of providing fundamental physical and chemical information on the ignition of bulk metals under different gravity levels. The metals used in the study, iron (Fe), titanium (Ti), zirconium (Zr), magnesium (Mg), zinc (Zn), and copper (Cu) were selected because of their importance as elements of structural metals and their simple chemical composition (pure metals instead of multi-component alloys to avoid complication in morphology and spectroscopic studies). These samples were also chosen to study the two different combustion modes experienced by metals: heterogeneous or surface oxidation, and homogeneous or gas-phase reaction. The experimental approach provides surface temperature profiles, spectroscopic measurements, surface morphology, x-ray spectrometry of metals specimens and their combustion products, and high-speed cinematography of the heating, ignition and combustion

  2. Undiagnosed illnesses and radioactive warfare.

    PubMed

    Duraković, Asaf

    2003-10-01

    . The analysis of the isotopic ratios identified non-depleted uranium. Studies of specimens collected in 2002 revealed uranium concentrations up to 200 times higher in the districts of Tora Bora, Yaka Toot, Lal Mal, Makam Khan Farm, Arda Farm, Bibi Mahro, Poli Cherki, and the Kabul airport than in the control population. Uranium levels in the soil samples from the bombsites show values two to three times higher than worldwide concentration levels of 2 to 3 mg/kg and significantly higher concentrations in water than the World Health Organization maximum permissible levels. This growing body of evidence undoubtedly puts the problem of prevention and solution of the DU contamination high on the priority list. PMID:14515407

  3. Hybridization of glutamate aspartate transaminase. Investigation of subunit interaction.

    PubMed

    Boettcher, B; Martinez-Carrion, M

    1975-10-01

    Glutamate aspartate transaminase (EC 2.6.1.1) is a dimeric enzyme with identical subunits with each active site containing pyridoxal 5'-phosphate linked via an internal Shiff's base to a lysine residue. It is not known if these sites interact during catalysis but negative cooperativity has been reported for binding of the coenzyme (Arrio-Dupont, M. (1972), Eur. J. Biochem. 30, 307). Also nonequivalence of its subunits in binding 8-anilinonaphthalene-1-sulfonate (Harris, H.E., and Bayley, P. M. (1975), Biochem. J. 145, 125), in modification of only a single tyrosine with full loss of activity (Christen, P., and Riordan, J.F. (1970), Biochemistry 9, 3025), and following modification with 5,5'-dithiobis(2-nitrobenzoic acid) (Cournil, I., and Arrio-Dupont, M. (1973), Biochemie 55, 103) has been reported. However, steady-state and transient kinetic methods as well as direct titration of the active site chromophore with substrates and substrate analogs have not revealed any cooperative phenomena (Braunstein, A. E. (1973), Enzymes, 3rd Ed. 9, 379). It was therefore decided that a more direct approach should be used to clarify the quistion of subunit interaction during the covalent phase of catalysis. To this end a hybrid method was devised in which a hybrid transaminase was prepared which contained one subunit with a functional active site while the other subunit has the internal Shiff's base reduced with NaBH4. The specific activities and amount of "actively bound" pyridoxal 5'-phosphate are both in a 2:1 ratio for the native and hybrid forms. Comparison of the steady-state kinetic properties of the hybrid and native enzyme forms shows that both forms gave parallel double reciprocal plots which is characteristic of the Ping-Pong Bi-Bi mechanism of transamination. The Km values for the substrates L-aspartic acid and alpha-ketoglutaric acid are nearly identical while the Vmax value for the hybrid is one-half the value of the native transaminase. It therefore appears that

  4. ALE3D Simulation and Measurement of Violence in a Fast Cookoff Experiment for LX-10

    SciTech Connect

    McClelland, M A; Maienschein, J L; Howard, W M; deHaven, M R

    2006-05-23

    Fast cookoff is of interest in the areas of fire hazard reduction and the development of directed energy systems for defense. During a fast cookoff (thermal explosion), high heat fluxes cause rapid temperature increases and ignition in thin boundary layers. We are developing ALE3D models to describe the thermal, chemical, and mechanical behavior during the heating, ignition, and explosive phases. The candidate models and numerical strategies are being evaluated using benchmark cookoff experiments. Fast cookoff measurements were made in a Scaled-Thermal-Explosion-eXperiment (STEX) for LX-10 (94.7% HMX, 5.3% Viton A) confined in a 4130 steel tube with reinforced end caps. Gaps were present at the side and top of the explosive charge to allow for thermal expansion. The explosive was heated until explosion using radiant heaters. Temperatures were measured using thermocouples positioned on the tube wall and in the explosive. During the explosion, the tube expansion and fragment velocities were measured with strain gauges, Photonic-Doppler-Velocimeters (PDVs), and micropower radar units. A fragment size distribution was constructed from fragments captured in Lexan panels. ALE3D models for chemical, thermal, and mechanical behavior were developed for the heating and explosive processes. A multi-step chemical kinetics model is employed for the HMX while a one-step model is used for the Viton. A pressure-dependent deflagration model is employed during the expansion. A Steinberg-Guinan model represents the mechanical behavior of the solid constituents while polynomial and gamma-law expressions are used for the equation of state of the solid and gas species, respectively. Parameters for the kinetics model were specified using measurements of the One-Dimensional-Time-to-Explosion (ODTX), while measurements for burn rate were employed to determine parameters in the burn front model. The simulations include radiative and conductive transport across the dynamic gaps between the

  5. Measurements and ALE3D Simulations for Violence in a Scaled Thermal Explosion Experiment with LX-10 and AerMet 100 Steel

    SciTech Connect

    McClelland, M A; Maienschein, J L; Yoh, J J; deHaven, M R; Strand, O T

    2005-06-03

    We completed a Scaled Thermal Explosion Experiment (STEX) and performed ALE3D simulations for the HMX-based explosive, LX-10, confined in an AerMet 100 (iron-cobalt-nickel alloy) vessel. The explosive was heated at 1 C/h until cookoff at 182 C using a controlled temperature profile. During the explosion, the expansion of the tube and fragment velocities were measured with strain gauges, Photonic-Doppler-Velocimeters (PDVs), and micropower radar units. These results were combined to produce a single curve describing 15 cm of tube wall motion. A majority of the metal fragments were captured and cataloged. A fragment size distribution was constructed, and a typical fragment had a length scale of 2 cm. Based on these results, the explosion was considered to be a violent deflagration. ALE3D models for chemical, thermal, and mechanical behavior were developed for the heating and explosive processes. A four-step chemical kinetics model is employed for the HMX while a one-step model is used for the Viton. A pressure-dependent deflagration model is employed during the expansion. The mechanical behavior of the solid constituents is represented by a Steinberg-Guinan model while polynomial and gamma-law expressions are used for the equation of state of the solid and gas species, respectively. A gamma-law model is employed for the air in gaps, and a mixed material model is used for the interface between air and explosive. A Johnson-Cook model with an empirical rule for failure strain is used to describe fracture behavior. Parameters for the kinetics model were specified using measurements of the One-Dimensional-Time-to-Explosion (ODTX), while measurements for burn rate were employed to determine parameters in the burn front model. The ALE3D models provide good predictions for the thermal behavior and time to explosion, but the predicted wall expansion curve is higher than the measured curve. Possible contributions to this discrepancy include inaccuracies in the chemical models

  6. "Positive and negative item wording and its influence on the Assessment of Callous-Unemotional Traits": Correction to Ray et al. (2015).

    PubMed

    2016-04-01

    Reports an error in "Positive and Negative Item Wording and Its Influence on the Assessment of Callous-Unemotional Traits" by James V. Ray, Paul J. Frick, Laura C. Thornton, Laurence Steinberg and Elizabeth Cauffman (Psychological Assessment, Advanced Online Publication, Jun 29, 2015, np). In the article, the sixth sentence of the second full paragraph in the Data Analyses subsection of the Method section should read "For k response categories, there are k-1 threshold parameters." (The following abstract of the original article appeared in record 2015-28939-001.) This study examined the item functioning of the Inventory of Callous-Unemotional Traits (ICU) in an ethnically diverse sample 1,190 of first-time justice-involved adolescents (mean age = 15.28 years, SD = 1.29). On elimination of 2 items, the total ICU score provided a reliable (internally consistent and stable) and valid (correlated with and predictive of measures of empathy, school conduct problems, delinquency, and aggression) continuous measure of callous and unemotional (CU) traits. A shortened, 10-item version of the total scale, developed from item response theory (IRT) analyses, appeared to show psychometric properties similar to those of the full ICU and, thus, could be used as an abbreviated measure of CU traits. Finally, item analyses and tests of validity suggested that the factor structure of the ICU reported in a large number of past studies could reflect method variance related to the ICU, including equal numbers of positively and negatively worded items. Specifically, positively worded items (i.e., items for which higher ratings are indicative of higher levels of CU traits) were more likely to be rated in the lower response categories, showed higher difficulty levels in IRT analyses (i.e., discriminated best at higher levels of CU traits), and were more highly correlated with measures of antisocial and aggressive behavior. On the basis of these findings, we recommend using the total ICU as

  7. The enzymatic and antioxidative stress response of Lemna minor to copper and a chloroacetamide herbicide.

    PubMed

    Obermeier, Michael; Schröder, Christian A; Helmreich, Brigitte; Schröder, Peter

    2015-12-01

    Lemna minor L., a widely used model plant for toxicity tests has raised interest for its application to phytoremediation due to its rapid growth and ubiquitous occurrence. In rural areas, the pollution of water bodies with heavy metals and agrochemicals poses a problem to surface water quality. Among problematic compounds, heavy metals (copper) and pesticides are frequently found in water bodies. To establish duckweed as a potential plant for phytoremediation, enzymatic and antioxidative stress responses of Lemna minor during exposure to copper and a chloroacetamide herbicide were investigated in laboratory studies. The present study aimed at evaluating growth and the antioxidative and glutathione-dependent enzyme activity of Lemna plants and its performance in a scenario for phytoremediation of copper and a chloroacetamide herbicide. Lemna minor was grown in Steinberg medium under controlled conditions. Plants were treated with CuSO4 (ion conc. 50 and 100 μg/L) and pethoxamide (1.25 and 2.5 μg/L). Measurements following published methods focused on plant growth, oxidative stress, and basic detoxification enzymes. Duckweed proved to survive treatment with the respective concentrations of both pollutants very well. Its growth was inhibited scarcely, and no visible symptoms occurred. On the cellular basis, accumulation of O2(-) and H2O2 were detected, as well as stress reactions of antioxidative enzymes. Duckweed detoxification potential for organic pollutants was high and increased significantly with incubation. Pethoxamide was found to be conjugated with glutathione. Copper was accumulated in the fronds at high levels, and transient oxidative defense reactions were triggered. This work confirms the significance of L. minor for the removal of copper from water and the conjugation of the selective herbicide pethoxamide. Both organic and inorganic xenobiotics induced different trends of enzymatic and antioxidative stress response. The strong increase of stress

  8. Residual Effects of Low-Dose Sublingual Zolpidem on Highway Driving Performance the Morning after Middle-of-the-Night Use

    PubMed Central

    Vermeeren, Annemiek; Vuurman, Eric F.P.M.; Leufkens, Tim R.M.; Van Leeuwen, Cees J.; Van Oers, Anita C.M.; Laska, Eugene; Rico, Salvador; Steinberg, Frank; Roth, Thomas

    2014-01-01

    Study Objective: To evaluate next-morning driving performance after middle-of-the-night use of zolpidem 3.5 mg in a buffered sublingual formulation (ZST). Design: Single-center, four-period, randomized, double-blind, placebo-controlled, crossover study. Setting: Maastricht University, The Netherlands. Participants: Forty healthy volunteers (20 females). Interventions: Single dose of ZST administered in the middle of the night at 3 and 4 h before driving, zopiclone 7.5 mg at bedtime 9 h before driving, and placebo. Measurements: Performance in a 100-km standardized highway driving test in normal traffic measuring standard deviation of lateral position (SDLP) — an index of weaving. Drug-placebo changes in SDLP > 2.5 cm were considered to reflect clinically relevant driving impairment. Result: For ZST, Max McNemar symmetry analyses showed that the proportion of drivers classified as impaired was increased 3 h after dosing (P < 0.012), but not 4 h after dosing. Mean increases in SDLP from placebo, although statistically significant, were small (1.46 cm [P < 0.0001] at 3 h and 0.83 cm [P = 0.0174] at 4 h). The morning after zopiclone, 45% of the drivers were classified as impaired with a mean increase in SDLP of 2.46 cm (P < 0.0001). There were no significant sex differences in effects of ZST and zopiclone. Conclusion: Zolpidem 3.5 mg in a buffered sublingual formulation has a minimal risk of impairing driving performance in the morning ≥ 4 hours after middle-of-the night use. When taken 3 hours before driving, the drug may have impairing effects so caution should be exercised if medication is taken other than as indicated. Clinical Trial Information: ClinicalTrials.gov Identifier: NCT01106859; Trial Name: Driving Performance After Middle of the Night Administration of 3.5 mg Zolpidem Tartrate Sublingual Tablet; http://clinicaltrials.gov/ct2/show/NCT01106859. Citation: Vermeeren A; Vuurman EF; Leufkens TR; Van Leeuwen CJ; Van Oers AC; Laska E; Rico S; Steinberg F

  9. Possible Signatures Of Kelvin-Helmholtz Waves On The Dusk Flank Of The Kronian Magnetopause

    NASA Astrophysics Data System (ADS)

    Cutler, Jack; Masters, Adam; Dougherty, Michele; Lucek, Elizabeth; Kanani, Sheila

    2010-05-01

    A comprehensive survey of crossings of both Saturn's magnetopause and bow shock on the dusk side between January 2007 and December 2007 was compiled, using data from the Cassini fluxgate magnetometer and the Cassini electron spectrometer. Bow shock and magnetopause crossings were determined by the criteria discussed in Masters et al., 2008 and Masters et al., 2009 [1] respectively. 396 magnetopause crossings and 165 bow shock crossings were identified with large spatial variation; the high temporal frequency of crossings combined with the large radial variation was indicative of highly dynamic boundaries. A set of magnetopause crossings occurring near the nose of the magnetopause on the 30th June and 1st July 2007 were then analysed using minimum variance analysis (MVA) of the magnetic field vectors over the crossing interval to determine the direction of the boundary normal at each crossing. Using MVA analysis again to calculate the maximum variance direction of the magnetopause normals, I found a clear preferred direction of variance of the normals. The normals were found to deviate by an average of 30° about the average normal direction in the plane of maximum variance, but only by 12° in the perpendicular plane. The observed oscillation of dawn side crossing normals (Masters et al., 2009) was not present throughout the whole dusk set, but was present for subsets, which is suggestive of wave activity. Considering the orientation between the magnetospheric magnetic field and the direction of maximum variance of the normals, the Kelvin-Helmholtz (K-H) instability is the likely driving force of these boundary perturbations. Current work involves analyzing two further magnetopause crossing sets, one further dusk-ward and one closer to noon (SLT), to identify whether K-H waves are also present at these locations. [1] Masters, A.; McAndrews, H. J.; Steinberg, J. T.; Thomsen, M. F.; Arridge, C. S.; Dougherty, M. K.; Billingham, L.; Schwartz, S. J.; Sergis, N

  10. STAT3 governs hyporesponsiveness and granzyme B-dependent suppressive capacity in human CD4+ T cells

    PubMed Central

    Schmetterer, Klaus G.; Neunkirchner, Alina; Wojta-Stremayr, Daniela; Leitner, Judith; Steinberger, Peter; Pickl, Winfried F.

    2015-01-01

    Signal transducer and activator of transcription 3 (STAT3) integrates key signals of cell surface immune receptors, yet its precise role in cluster of differentiation (CD)4+ T cells is not well-established. Current research has indicated T-helper cell 17–inducing roles but also tolerogenic roles. To address this issue, human T cells were transduced with the constitutively active STAT3 mutant STAT3C. Following stimulation, STAT3C+ T cells up-regulated IL-10 (4.1 ± 0.5-fold; P < 0.001) and granzyme B (2.5 ± 1.2, P < 0.05) secretion, combined with significantly reduced IFN-γ (35 ± 5%), IL-2 (57 ± 4%), TNF-α (64 ± 8%), and IL-13 (89 ± 3%) secretion (P < 0.001). CD3/CD2- or CD3/CD28-activated STAT3C+ T cells revealed reduced proliferation (53.4 ± 23.5% and 70.5 ± 10.4%, respectively), which was independent of IL-10 production and significantly suppressed effector T cell proliferation by 68.7 ± 10.6% and 65.9 ± 2.6%, respectively (P < 0.001). Phenotypically, STAT3C-transgenic CD4+ T cells resembled effector T cells regarding expression of T regulatory cell markers, but up-regulated granzyme B expression levels by 2.4-fold (P < 0.05). Suppression was cell contact dependent and mediated by granzyme B-induced cell death, but was independent of IL-10 and TGF-β. Notably, peripheral blood CD4+CD45RA−lymphocyte activation gene-3+CD49+ type 1 regulatory T cells revealed activation-induced hyperphosphorylation of STAT3. In agreement, pharmacological inhibition of STAT3 activation partially reverted hyporesponsiveness of peripheral type 1 regulatory T cells (increasing their division index from 0.46 ± 0.11 to 0.89 ± 0.04; P < 0.01). These observations indicate a clear-cut relation between activation of STAT3 and the acquisition of a tolerogenic program, which is also used by peripheral blood type 1 regulatory T cells.—Schmetterer, K. G., Neunkirchner, A., Wojta-Stremayr, D., Leitner, J., Steinberger, P., Pickl, W. F. STAT3 governs hyporesponsiveness and

  11. Examining the effects of students' classroom expectations on undergraduate biology course reform

    NASA Astrophysics Data System (ADS)

    Hall, Kristi Lyn

    In this dissertation, I perform and compare three studies of introductory biology students' classroom expectations -- what students expect to be the nature of the knowledge that they are learning, what they think they should be (or are) doing in order to learn, and what they think they should be (or are) doing in order to be successful. Previous work has shown that expectations can impact how students approach learning, yet biology education researchers have been reluctant to acknowledge or address the effects of student expectations on curricular reform (NRC, 2012). Most research in biology education reform has focused on students' conceptual understandings of biology and the efficacy of specific changes to content and pedagogy. The current research is lacking a deeper understanding of how students perceive the classroom environment and how those perceptions can shape students' interactions with the content and pedagogy. For present and future reforms in biology to reach their full potential, I argue that biology education should actively address the different ways students think about and approach learning in biology classes. The first study uses a Likert-scale instrument, adapted from the Maryland Physics Expectations Survey (Redish, Saul, & Steinberg, 1998). This new survey, the Maryland Biology Expectations Survey (MBEX) documents two critical results in biology classrooms: (i) certain student-centered pedagogical contexts can produce favorable changes in students' expectations, and (ii) more traditional classroom contexts appear to produce negative epistemological effects. The second study utilizes a modified version of the MBEX and focuses on students' interdisciplinary views. This study documents that: (i) biology students have both discipline-specific and context-specific classroom expectations, (ii) students respond more favorably to interdisciplinary content in the biology courses we surveyed (as opposed to biology content introduced into the physics

  12. Modified porous tantalum rod technique for the treatment of femoral head osteonecrosis

    PubMed Central

    Pakos, Emilios E; Megas, Panayiotis; Paschos, Nikolaos K; Syggelos, Spyridon A; Kouzelis, Antonios; Georgiadis, Georgios; Xenakis, Theodoros A

    2015-01-01

    AIM: To study a modified porous tantalum technique for the treatment of osteonecrosis of the femoral head. METHODS: The porous tantalum rod was combined with endoscopy, curettage, autologous bone grafting and use of bone marrow aspirates from iliac crest aspiration in 49 patients (58 hips) with a mean age of 38 years. The majority of the patients had idiopathic osteonecrosis, followed by corticosteroid-induced osteonecrosis. Thirty-eight hips were of Steinberg stage II disease and 20 hips were of stage III disease. Patients were followed for 5 years and were evaluated clinically with the Merle D’Aubigne and Postel score and radiologically. The primary outcome of the study was survival based on the conversion to total hip arthroplasty (THA). Secondary outcomes included deterioration of the osteonecrosis to a higher disease stage at 5 years compared to the preoperative period and identification of factors that were associated with survival. The Kaplan-Meier survival analysis was performed to evaluate the survivorship of the prosthesis, and the Fisher exact test was performed to test associations between various parameters with survival. RESULTS: No patient developed any serious intraoperative or postoperative complication including implant loosening or migration and donor site morbidity. During the 5-year follow up, 1 patient died, 7 patients had disease progression and 4 hips were converted to THA. The 5-year survival based on conversion to THA was 93.1% and the respective rate based on disease progression was 87.9%. Stage II disease was associated with statistically significant better survival rates compared to stage III disease (P = 0.04). The comparison between idiopathic and non-idiopathic osteonecrosis and between steroid-induced and non-steroid-induced osteonecrosis did not showed any statistically significant difference in survival rates. The clinical evaluation revealed statistically significantly improved Merle d’Aubigne scores at 12 mo postoperatively

  13. Global Paleobathymetry for the Cenomanian-Turonian (90 Ma)

    NASA Astrophysics Data System (ADS)

    Goswami, A.; Olson, P.; Hinnov, L. A.; Gnanadesikan, A.

    2014-12-01

    , C., Steinberger, B., Heine, C., 2008a, Science, 319, 1357-1362. Scotese, C., 2011, PALEOMAP Project, Arlington, Texas. Turcotte, D., Schubert, G., 2002, Cambridge University Press, Cambridge, 456 p. Whittaker, J., Goncharov, A., Williams, S., Müller, R., Leitchenkov, G., 2013, Geochemistry, Geophysics, Geosystems. DOI:10.1002/ggge.20181

  14. Polyphase basin evolution of the Vienna Basin inferred from 3D visualization of sedimentation setting and quantitative subsidence

    NASA Astrophysics Data System (ADS)

    Lee, Eun Young; Novotny, Johannes; Wagreich, Michael

    2016-04-01

    This study analyzed and visualized data from 210 wells using a MATLAB-based program (BasinVis 1.0) for 3D visualization of sediment distribution, thickness, and quantitative subsidence of the northern and central Vienna Basin. The sedimentation settings for selected horizons were visualized to 3D sediment distribution maps, isopach maps, and cross-sections. Subsidence of the study area resulted in 3D subsidence depth and rate maps of basement and tectonic subsidences. Due to the special position of the Vienna Basin, the basin evolution was influenced by the regional tectonics of surrounding units. The 2D/3D maps provided insights into the polyphase evolution of the Vienna Basin, which is closely related to changes in the changing regional stress field and the paleoenvironmental setting. In the Early Miocene, the sedimentation and subsidence were shallow and E-W/NE-SW trending, indicating the development of piggy-back basins. During the late Early Miocene, maps show wider sedimentation and abruptly increasing subsidence by sinistral strike-slip faults, which initiated the Vienna pull-apart basin system. The sediments of the Early Miocene were supplied through a small deltaic system entering from the south. After thin sedimentation and shallow subsidence of the early Middle Miocene, the development of the Vienna Basin was controlled and accelerated mainly by NE-SW trending synsedimentary normal faults, especially the Steinberg fault. From the Middle Miocene, the subsidence was decreasing overall, however the tectonic subsidence show regionally different patterns. This study suggests that a major tensional regime change, from transtension to E-W extension, caused laterally varying subsidence across the Vienna Basin. The Late Miocene was characterized by the slowing down of basement and tectonic subsidence. From the middle Middle to Late Miocene, enormous amount of sediments supplied by a broad paleo-Danube delta complex on the western flank of the basin. The latest

  15. Constraints on the mantle and lithosphere dynamics from the observed geoid with the effect of visco-elasto-plastic rheology in the upper 300 km

    NASA Astrophysics Data System (ADS)

    Osei Tutu, Anthony; Steinberger, Bernhard; Rogozhina, Irina; Sobolev, Stephan

    2015-04-01

    used. Finally, given significant dispersion of geodynamic predictions from different seismic tomography models currently available, we further look for seismic models that provide predictions closest to observations at both regional and global scales. References 1. Hager B.H & O'Connell R.J., 1981. A simple global model of plate dynamics and mantle convection, J.Geophys. Res. 86, 4843-4867 2. Popov A.A., Sobolev S.V., 2008. SLIM3D: A tool for three-dimensional thermo- mechanical modelling of lithospheric deformation with elasto-visco-plastic rheology, J.pepi.2008.03.007 3. Steinberger B., 2014. Dynamic topography: A comparison between observations and models based on seismic tomography. (Submitted) 4. Becker T and Boschi L., 2002, A comparison of tomographic and geodynamic mantle models. , J.Geophys. Res. 115, 0148-0227

  16. Global Dynamic Numerical Simulations of Plate Tectonic Reorganizations

    NASA Astrophysics Data System (ADS)

    Morra, G.; Quevedo, L.; Butterworth, N.; Matthews, K. J.; Müller, D.

    2010-12-01

    We use a new numerical approach for global geodynamics to investigate the origin of present global plate motion and to identify the causes of the last two global tectonic reorganizations occurred about 50 and 100 million years ago (Ma) [1]. While the 50 Ma event is the most well-known global plate-mantle event, expressed by the bend in the Hawaiian-Emperor volcanic chain, a prominent plate reorganization at about 100 Ma, although presently little studied, is clearly indicated by a major bend in the fracture zones in the Indian Ocean and by a change in Pacific plate motion [2]. Our workflow involves turning plate reconstructions into surface meshes that are subsequently employed as initial conditions for global Boundary Element numerical models. The tectonic setting that anticipates the reorganizations is processed with the software GPlates, combining the 3D mesh of the paleo-plate morphology and the reconstruction of paleo-subducted slabs, elaborated from tectonic history [3]. All our models involve the entire planetary system, are fully dynamic, have free surface, are characterized by a spectacular computational speed due to the simultaneous use of the multi-pole algorithm and the Boundary Element formulation and are limited only by the use of sharp material property variations [4]. We employ this new tool to unravel the causes of plate tectonic reorganizations, producing and comparing global plate motion with the reconstructed ones. References: [1] Torsvik, T., Müller, R.D., Van der Voo, R., Steinberger, B., and Gaina, C., 2008, Global Plate Motion Frames: Toward a unified model: Reviews in Geophysics, VOL. 46, RG3004, 44 PP., 2008 [2] Wessel, P. and Kroenke, L.W. Pacific absolute plate motion since 145 Ma: An assessment of the fixed hot spot hypothesis. Journal of Geophysical Research, Vol 113, B06101, 2008 [3] L. Quevedo, G. Morra, R. D. Mueller. Parallel Fast Multipole Boundary Element Method for Crustal Dynamics, Proceeding 9th World Congress and 4th Asian

  17. Analysis and suppression of instabilities in viscoelastic flows

    NASA Astrophysics Data System (ADS)

    Kumar, Karkala Arun

    2001-10-01

    The viscoelastic character of polymer solutions and melts gives rise to instabilities not seen in the flows of Newtonian liquids. In this thesis, we computationally study four such instabilities. The first instability we discuss is melt fracture, which takes the form of gross distortions of the polymer surface during extrusion. This instability is linked to multiplicity in the slip curve. We show here that when the dependence of slip velocity on pressure is taken into account, multiplicity in the slip law does not necessarily imply a multi-valued flow curve or melt fracture. Next, we study the ``filament-stretching'' instability, which takes the form of non-axisymmetric deviations of the free surface of a polymeric liquid bridge being extended between two parallel plates. We model the portion of the filament near the endplates as an elastic membrane enclosing an incompressible fluid and show that this is unstable to non-axisymmetric disturbances. The third instability we discuss is the purely elastic instability in Dean flow. This instability is linked to elastic instabilities in more complicated and industrially important coating flows with curved streamlines. We show how the addition of a small secondary axial flow in a steady or periodic fashion can significantly delay the onset of the instability. Recent experimental observations by Groisman and Steinberg ( Phys. Rev. Lett. 78(8), 1460-1463, 1997) and Baumert and Muller (Phys. Fluids, 9(3), 566-586, 1999) have shown the formation of spatially isolated, stationary, axisymmetric patterns in the nonlinear regime of circular Couette flow, termed ``diwhirls'' or ``flame patterns.'' Modeling these patterns is complicated by the absence of a stationary bifurcation in isothermal circular Couette flow. We show here how these solutions may be accessed by numerical continuation from stationary bifurcations in Couette-Dean flows. Although the solutions we compute are unstable, they show qualitative and quantitative

  18. Deep structure and origin of active volcanoes in China

    NASA Astrophysics Data System (ADS)

    Zhao, D.

    2010-12-01

    Recent geophysical studies have provided important constraints on the deep structure and origin of the active intraplate volcanoes in Mainland China. Magmatism in the western Pacific arc and back-arc areas is caused by the corner flow in the mantle wedge and dehydration of the subducting slab (e.g., Zhao et al., 2009a), while the intraplate magmatism in China has different origins. The active volcanoes in Northeast China (such as the Changbai and Wudalianchi) are caused by hot upwelling in the big mantle wedge (BMW) above the stagnant slab in the mantle transition zone and deep slab dehydration as well (Zhao et al., 2009b). The Tengchong volcano in Southwest China is caused by a similar process in the BMW above the subducting Burma microplate (or Indian plate) (Lei et al., 2009a). The Hainan volcano in southernmost China is a hotspot fed by a lower-mantle plume which may be associated with the Pacific and Philippine Sea slabs' deep subduction in the east and Indian slab's deep subduction in the west down to the lower mantle (Lei et al., 2009b; Zhao, 2009). The stagnant slab finally collapses down to the bottom of the mantle, which can trigger the upwelling of hot mantle materials from the lower mantle to the shallow mantle beneath the subducting slabs and may cause the slab-plume interactions (Zhao, 2009). References Lei, J., D. Zhao, Y. Su, 2009a. Insight into the origin of the Tengchong intraplate volcano and seismotectonics in southwest China from local and teleseismic data. J. Geophys. Res. 114, B05302. Lei, J., D. Zhao, B. Steinberger et al., 2009b. New seismic constraints on the upper mantle structure of the Hainan plume. Phys. Earth Planet. Inter. 173, 33-50. Zhao, D., 2009. Multiscale seismic tomography and mantle dynamics. Gondwana Res. 15, 297-323. Zhao, D., Z. Wang, N. Umino, A. Hasegawa, 2009a. Mapping the mantle wedge and interplate thrust zone of the northeast Japan arc. Tectonophysics 467, 89-106. Zhao, D., Y. Tian, J. Lei, L. Liu, 2009b. Seismic

  19. Designing across ages: Multi-agent-based models and learning electricity

    NASA Astrophysics Data System (ADS)

    Sengupta, Pratim

    Electricity is regarded as one of the most challenging topics for students at all levels -- middle school -- college (Cohen, Eylon, & Ganiel, 1983; Belcher & Olbert, 2003; Eylon & Ganiel, 1990; Steinberg et al., 1985). Several researchers have suggested that naive misconceptions about electricity stem from a deep incommensurability (Slotta & Chi, 2006; Chi, 2005) or incompatibility (Chi, Slotta & Leauw, 1994; Reiner, Slotta, Chi, & Resnick, 2000) between naive and expert knowledge structures. I first present an alternative theoretical framework that adopts an emergent levels-based perspective as proposed by Wilensky & Resnick (1999). From this perspective, macro-level phenomena such as electric current and resistance, as well as behavior of linear electric circuits, can be conceived of as emergent from simple, body-syntonic interactions between electrons and ions in a circuit. I argue that adopting such a perspective enables us to reconceive commonly noted misconceptions in electricity as behavioral evidences of "slippage between levels" -- i.e., these misconceptions appear when otherwise productive knowledge elements are sometimes inappropriately activated due to certain macro-level phenomenological cues only -- and, that the same knowledge elements when activated due to phenomenological cues at both micro- and macro-levels, can engender a deeper, expert-like understanding. I will then introduce NIELS (NetLogo Investigations In Electromagnetism, Sengupta & Wilensky, 2006, 2008, 2009), a low-threshold high-ceiling (LTHC) learning environment of multi-agent-based computational models that represent phenomena such as electric current and resistance, as well as the behavior of linear electric circuits, as emergent. I also present results from implementations of NIELS in 5th, 7th and 12th grade classrooms that show the following: (a) how leveraging certain "design elements" over others in NIELS models can create new phenomenological cues, which in turn can be

  20. Seismic and Geodynamic Constraints on Compositional Heterogeneity in the Lower Mantle: Implications for Deeply-Rooted Hot Upwellings Under the African and Pacific Plates

    NASA Astrophysics Data System (ADS)

    Forte, A. M.; Glisovic, P.; Rowley, D. B.; Simmons, N. A.; Grand, S. P.; Lu, C.

    2014-12-01

    We present the results of a series of tests that probe the possible existence of compositionally distinct material in the central core of the LLSVPs under the African and Pacific plates using tomography-based mantle flow models that employ several independently-derived viscosity profiles (Mitrovica & Forte 2004, Behn et al. 2004, Steinberger & Calderwood 2006, Forte et al. 2010). We also consider four global tomography models derived from seismic shear velocity data alone (Grand 2002, Panning & Romanowicz 2006, Kustowski et al. 2008, Ritsema et al. 2011). The possible combinations of viscosity and tomography models yield 16 different tests for compositional heterogeneity inside the LLSVPs. In all tests we begin with a mineral physical scaling between lower-mantle shear velocity and density anomalies that assumes thermal effects are dominant everywhere, including within the LLSVPs. We find it is not possible, in any of the tests, to obtain a satisfactory fit to surface geodynamic data, especially the global, long-wavelength gravity anomalies and space-geodetic inferences of excess CMB flattening with a purely thermal interpretation of lower-mantle heterogeneity. If we introduce compositionally-distinct material in the central portions of the LLSVPs, all tests show a notable improvement in the fit to the gravity anomaly and CMB ellipticity data. An optimal reconciliation of the gravity and CMB data is obtained by extending compositional heterogeneity upwards, with maximum-amplitude in the seismic D"-layer and tapering off to negligible values in the mid-mantle. A robust assessment of the dynamical impact of this deeply-rooted compositional heterogeneity is obtained with maps of "mean" convective flow, by averaging the results of all 16 test cases. We find (see map below) dominant lower-mantle upwellings below the axis of the East Pacific Rise (EPR), and under the Caroline Islands in the Western Pacific. Under the African plate we find large-scale upwellings under the

  1. The geological evolution of Merapi volcano, Central Java, Indonesia

    NASA Astrophysics Data System (ADS)

    Gertisser, Ralf; Charbonnier, Sylvain J.; Keller, Jörg; Quidelleur, Xavier

    2012-07-01

    Merapi is an almost persistently active basalt to basaltic andesite volcanic complex in Central Java (Indonesia) and often referred to as the type volcano for small-volume pyroclastic flows generated by gravitational lava dome failures (Merapi-type nuées ardentes). Stratigraphic field data, published and new radiocarbon ages in conjunction with a new set of 40K-40Ar and 40Ar-39Ar ages, and whole-rock geochemical data allow a reassessment of the geological and geochemical evolution of the volcanic complex. An adapted version of the published geological map of Merapi [(Wirakusumah et al. 1989), Peta Geologi Gunungapi Merapi, Jawa Tengah (Geologic map of Merapi volcano, Central Java), 1:50,000] is presented, in which eight main volcano stratigraphic units are distinguished, linked to three main evolutionary stages of the volcanic complex—Proto-Merapi, Old Merapi and New Merapi. Construction of the Merapi volcanic complex began after 170 ka. The two earliest (Proto-Merapi) volcanic edifices, Gunung Bibi (109 ± 60 ka), a small basaltic andesite volcanic structure on Merapi's north-east flank, and Gunung Turgo and Gunung Plawangan (138 ± 3 ka; 135 ± 3 ka), two basaltic hills in the southern sector of the volcano, predate the Merapi cone sensu stricto. Old Merapi started to grow at ~30 ka, building a stratovolcano of basaltic andesite lavas and intercalated pyroclastic rocks. This older Merapi edifice was destroyed by one or, possibly, several flank failures, the latest of which occurred after 4.8 ± 1.5 ka and marks the end of the Old Merapi stage. The construction of the recent Merapi cone (New Merapi) began afterwards. Mostly basaltic andesite pyroclastic and epiclastic deposits of both Old and New Merapi (<11,792 ± 90 14C years BP) cover the lower flanks of the edifice. A shift from medium-K to high-K character of the eruptive products occurred at ~1,900 14C years BP, with all younger products having high-K affinity. The radiocarbon record points towards an

  2. Feasibility of using benthic invertebrates as indicators of stream quality in Hawaii

    USGS Publications Warehouse

    Wolff, Reuben H.

    2005-01-01

    Macroinvertebrates were collected from 19 sites on 14 streams on the island of Oahu and from 9 sites on 7 streams on the island of Kauai to evaluate associations between macroinvertebrate assemblages and environmental variables and to determine whether or not it would be feasible, in future studies, to develop macroinvertebrate metrics that would indicate stream quality based on the macroinvertebrate assemblages and/or components of the assemblages. The purpose of applying rapid bioassessment techniques is to identify stream quality problems and to document changes in stream quality. Samples were collected at 10 sites in 1999, 3 sites in 2000, and 5 sites in 2003 on Oahu and at 9 sites on Kauai in 2003. Additionally, multiple year and multiple reach samples were collected at 1 site on Oahu. Macroinvertebrates were collected primarily from boulder/cobble riffles or from the fastest flowing habitat when riffles were absent. Although most streams in Hawaii originate in mountainous, forested areas, the lower reaches often drain urban, agricultural, or mixed land-use areas. The macroinvertebrate community data were used to identify metrics that could best differentiate between sites according to levels of environmental impairment. Environmental assessments were conducted using land-use/land-cover data, bed-sediment and fish-tissue contaminant data, and reach-level environmental data using a calibration set of 15 sites. The final scores of the environmental assessments were used to classify the sites into three categories of impairment: mild, moderate or severe. A number of invertebrate metrics were then tested and calibrated to the environmental assessments scores. The individual metrics that were the best at discerning environmental assessments among the sites were combined into a multimetric benthic index of biotic integrity (BIBI). These metrics were: total invertebrate abundance, taxa richness, insect relative abundance, amphipod abundance, crayfish presence or

  3. Mechanism and Significance of Post-Translational Modifications in the Large (LS) and Small (SS) Subunits of Ribulose-1,5 Bisphosphate Carboxylase/Oxygenase

    SciTech Connect

    Houtz, Robert, L.

    2012-11-09

    . Additionally, the tight initial binding of Rubisco LSMT to Rubisco also allowed us to design a novel immobilized complex between Rubisco and Rubisco LSMT, which allowed for an unambiguous demonstration of the requirement for trimethyllysine formation prior to disassociation of the Rubisco LSMT:Rubisco complex, and therefore proof of the processive mechanism for methyl group transfer. These kinetic studies also demonstrated that an important factor has been overlooked in all kinetic analyses of SET domain protein methyltransferases reported to date. This factor is the influence of the low turnover number for SET domain protein methyltransferases and how, relative to the time-frame of kinetic enzyme assays, this can generate changes in kinetic profiles shifting reciprocal plot patterns from random/ordered bi-bi to the real kinetic reaction mechanism plots of ping-pong. Although the ternary complexes of Rubisco LSMT with S-Adenosylhomocysteine and lysine and monomethyllysine were informative in regard to reaction mechanism, they were not helpful in identifying the mechanism used by Rubisco LSMT for determining substrate specificity. We were unsuccessful at obtaining ternary complexes of Rubisco LSMT with bound synthetic polypeptide substrates, as has been reported for several histone methyltransferases. However, we were able to model a polypeptide sequence corresponding to the N-terminal region of the LS of Rubisco into the apparent substrate binding cleft in Rubisco LSMT. Knowledge of the determinants of polypeptide substrate specificity are important for identifying possible alternate substrates, as well as the possibility of generating more desirable substrates amenable to site-directed mutagenesis experiments unlike Rubisco. We determined that Rubisco LSMT is capable of methylating synthetic polypeptide mimics of the N-terminal region of the LS, both free as well as conjugated to keyhole limpet hemacyanin, but with considerable less efficiency than intact holoenzyme.

  4. Biomimetic Production of Hydrogen

    NASA Astrophysics Data System (ADS)

    Gust, Devens

    2004-03-01

    organism. Some possible approaches to achieving this will be discussed. References (1) Gust, D.; Moore, T. A.; Moore, A. L. "Mimicking photosynthetic solar energy transduction," Acc. Chem. Res. 2001, 34, 40-48. (2) Kodis, G.; Liddell, P. A.; de la Garza, L.; Clausen, P. C.; Lindsey, J. S.; Moore, A. L.; Moore, T. A.; Gust, D. "Efficient energy transfer and electron transfer in an artificial photosynthetic antenna-reaction center complex," J. Phys. Chem. A 2002, 106, 2036-2048. (3) Liddell, P. A.; Kuciauskas, D.; Sumida, J. P.; Nash, B.; Nguyen, D.; Moore, A. L.; Moore, T. A.; Gust, D. "Photoinduced charge separation and charge recombination to a triplet state in a carotene-porphyrin-fullerene triad," J. Am. Chem. Soc. 1997, 119, 1400-1405. (4) Steinberg-Yfrach, G.; Liddell, P. A.; Hung, S.-C.; Moore, A. L.; Gust, D.; Moore, T. A. "Artificial photosynthetic reaction centers in liposomes: Photochemical generation of transmembrane proton potential," Nature 1997, 385, 239-241. (5) Steinberg-Yfrach, G.; Rigaud, J.-L.; Durantini, E. N.; Moore, A. L.; Gust, D.; Moore, T. A. "Light-driven production of ATP catalyzed by F0F1-ATP synthase in an artificial photosynthetic membrane," Nature 1998, 392, 479-482. (6) de la Garza, L.; Jeong, G.; Liddell, P. A.; Sotomura, T.; Moore, T. A.; Moore, A. L.; Gust, D. "Enzyme-based photoelectrochemical biofuel cell," J. Phys. Chem. B 2003, 107, 10252-10260.

  5. The Solid Earth Research and Teaching Environment, a new software framework to share research tools in the classroom and across disciplines

    NASA Astrophysics Data System (ADS)

    Milner, K.; Becker, T. W.; Boschi, L.; Sain, J.; Schorlemmer, D.; Waterhouse, H.

    2009-12-01

    The Solid Earth Teaching and Research Environment (SEATREE) is a modular and user-friendly software framework to facilitate the use of solid Earth research tools in the classroom and for interdisciplinary research collaboration. SEATREE is open source and community developed, distributed freely under the GNU General Public License. It is a fully contained package that lets users operate in a graphical mode, while giving more advanced users the opportunity to view and modify the source code. Top level graphical user interfaces which initiate the calculations and visualize results, are written in the Python programming language using an object-oriented, modern design. Results are plotted with either Matlab-like Python libraries, or SEATREE’s own Generic Mapping Tools wrapper. The underlying computational codes used to produce the results can be written in any programming language and accessed through Python wrappers. There are currently four fully developed science modules for SEATREE: (1) HC is a global geodynamics tool based on a semi-analytical mantle-circulation program based on work by B. Steinberger, Becker, and C. O'Neill. HC can compute velocities and tractions for global, spherical Stokes flow and radial viscosity variations. HC is fast enough to be used for classroom instruction, for example to let students interactively explore the role of radial viscosity variations for global geopotential (geoid) anomalies. (2) ConMan wraps Scott King’s 2D finite element mantle convection code, allowing users to quickly observe how modifications to input parameters affect heat flow over time. As seismology modules, SEATREE includes, (3), Larry, a global, surface wave phase-velocity inversion tool and, (4), Syn2D, a Cartesian tomography teaching tool for ray-theory wave propagation in synthetic, arbitrary velocity structure in the presence of noise. Both underlying programs were contributed by Boschi. Using Syn2D, students can explore, for example, how well a given

  6. Numerical Modeling of Deep Mantle Convection: Advection and Diffusion Schemes for Marker Methods

    NASA Astrophysics Data System (ADS)

    Mulyukova, Elvira; Dabrowski, Marcin; Steinberger, Bernhard

    2013-04-01

    Thermal and chemical evolution of Earth's deep mantle can be studied by modeling vigorous convection in a chemically heterogeneous fluid. Numerical modeling of such a system poses several computational challenges. Dominance of heat advection over the diffusive heat transport, and a negligible amount of chemical diffusion results in sharp gradients of thermal and chemical fields. The exponential dependence of the viscosity of mantle materials on temperature also leads to high gradients of the velocity field. The accuracy of many numerical advection schemes degrades quickly with increasing gradient of the solution, while the computational effort, in terms of the scheme complexity and required resolution, grows. Additional numerical challenges arise due to a large range of length-scales characteristic of a thermochemical convection system with highly variable viscosity. To examplify, the thickness of the stem of a rising thermal plume may be a few percent of the mantle thickness. An even thinner filament of an anomalous material that is entrained by that plume may consitute less than a tenth of a percent of the mantle thickness. We have developed a two-dimensional FEM code to model thermochemical convection in a hollow cylinder domain, with a depth- and temperature-dependent viscosity representative of the mantle (Steinberger and Calderwood, 2006). We use marker-in-cell method for advection of chemical and thermal fields. The main advantage of perfoming advection using markers is absence of numerical diffusion during the advection step, as opposed to the more diffusive field-methods. However, in the common implementation of the marker-methods, the solution of the momentum and energy equations takes place on a computational grid, and nodes do not generally coincide with the positions of the markers. Transferring velocity-, temperature-, and chemistry- information between nodes and markers introduces errors inherent to inter- and extrapolation. In the numerical scheme

  7. In situ measurement of mesopelagic particle sinking rates and the control of carbon transfer to the ocean interior during the Vertical Flux in the Global Ocean (VERTIGO) voyages in the North Pacific

    NASA Astrophysics Data System (ADS)

    Trull, T. W.; Bray, S. G.; Buesseler, K. O.; Lamborg, C. H.; Manganini, S.; Moy, C.; Valdes, J.

    2008-07-01

    sinking slower than 137 m d -1. At K2, less than 1% of the POC flux sank at >820 m d -1, but a large fraction (˜15-45%) of the flux was contributed by other fast-sinking classes (410 and 205 m d -1). PIC and BSi minerals were not present in higher proportions in the faster sinking fractions, but the observations were too limited to rule out a ballasting contribution to the control of sinking rates. Photographic evidence for a wide range of particle types within individual sinking-rate fractions suggests that biological processes that set the porosity and shape of particles are also important and may mask the role of minerals. Comparing the spectrum of sinking rates observed at K2 with the power-law profile of flux attenuation with depth obtained from other VERTIGO sediment traps deployed at multiple depths [Buesseler, K.O., Lamborg, C.H., Boyd, P.W., Lam, P.J., Trull, T.W., Bidigare, R.R., Bishop, J.K.B., Casciotti, K.L., Dehairs, F., Elskens, M., Honda, M., Karl, D.M., Siegel, D., Silver, M., Steinberg, D., Valdes, J., Van Mooy, B., Wilson, S.E., 2007b. Revisiting carbon flux through the Ocean's twilight zone. Science 316(5824), 567-570, doi: 10.1126/science.1137959] emphasizes the importance of particle transformations within the mesopelagic zone in the control of carbon transport to the ocean interior.

  8. New 40Ar/39Ar age progression for the Louisville hot spot trail and implications for inter-hot spot motion

    NASA Astrophysics Data System (ADS)

    Koppers, Anthony A. P.; Gowen, Molly D.; Colwell, Lauren E.; Gee, Jeffrey S.; Lonsdale, Peter F.; Mahoney, John J.; Duncan, Robert A.

    2011-12-01

    In this study we present 42 new 40Ar/39Ar incremental heating age determinations that contribute to an updated age progression for the Louisville seamount trail. Louisville is the South Pacific counterpart to the Hawaiian-Emperor seamount trail, both trails representing intraplate volcanism over the same time interval (˜80 Ma to present) and being examples of primary hot spot lineaments. Our data provide evidence for an age-progressive trend from 71 to 21 Ma. Assuming fixed hot spots, this makes possible a direct comparison to the Hawaiian-Emperor age progression and the most recent absolute plate motion (APM) model (WK08G) of Wessel and Kroenke (2008). We observe that for the Louisville seamount trail the measured ages are systematically older relative to both the WK08G model predictions and Hawaiian seamount ages, with offsets ranging up to 6 Myr. Taking into account the uncertainty about the duration of eruption and magmatic succession at individual Louisville volcanoes, these age offsets should be considered minimum estimates, as our sampling probably tended to recover the youngest lava flows. These large deviations point to either a contribution of inter-hot spot motion between the Louisville and Hawaiian hot spots or to a more easterly location of the Louisville hot spot than the one inferred in the WK08G model. Both scenarios are investigated in this paper, whereby the more eastern hot spot location (52.0°S, 134.5°W versus 52.4°S, 137.2°W) reduces the average age offset, but still results in a relatively large maximum offset of 3.7 Myr. When comparing the new ages to the APM models (S04P, S04G) by Steinberger et al. (2004) that attempt to compensate for the motion of hot spots in the Pacific (Hawaii) or globally (Hawaii, Louisville, Reunion and Walvis), the measured and predicted ages are more in agreement, showing only a maximum offset of 2.3 Myr with respect to the S04G model. At face value these more advanced APM models, which consider both plate and

  9. Pions to Quarks

    NASA Astrophysics Data System (ADS)

    Brown, Laurie Mark; Dresden, Max; Hoddeson, Lillian

    2009-01-01

    Part I. Introduction; 1. Pions to quarks: particle physics in the 1950s Laurie M Brown, Max Dresden and Lillian Hoddeson; 2. Particle physics in the early 1950s Chen Ning Yang; 3. An historian's interest in particle physics J. L. Heilbron; Part II. Particle discoveries in cosmic rays; 4. Cosmic-ray cloud-chamber contributions to the discovery of the strange particles in the decade 1947-1957 George D. Rochester; 5. Cosmic-ray work with emulsions in the 1940s and 1950s Donald H. Perkins; Part III. High-energy nuclear physics; Learning about nucleon resonances with pion photoproduction Robert L. Walker; 7. A personal view of nucleon structure as revealed by electron scattering Robert Hofstadter; 8. Comments on electromagnetic form factors of the nucleon Robert G. Sachs and Kameshwar C. Wali; Part IV. The new laboratory; 9. The making of an accelerator physicist Matthew Sands; 10. Accelerator design and construction in the 1950s John P. Blewett; 11. Early history of the Cosmotron and AGS Ernest D. Courant; 12. Panel on accelerators and detectors in the 1950s Lawrence W. Jones, Luis W. Alvarez, Ugo Amaldi, Robert Hofstadter, Donald W. Kerst, Robert R. Wilson; 13. Accelerators and the Midwestern Universities Research Association in the 1950s Donald W. Kerst; 14. Bubbles, sparks and the postwar laboratory Peter Galison; 15. Development of the discharge (spark) chamber in Japan in the 1950s Shuji Fukui; 16. Early work at the Bevatron: a personal account Gerson Goldhaber; 17. The discovery of the antiproton Owen Chamberlain; 18. On the antiproton discovery Oreste Piccioni; Part V. The Strange Particles; 19. The hydrogen bubble chamber and the strange resonances Luis W. Alvarez; 20. A particular view of particle physics in the fifties Jack Steinberger; 21. Strange particles William Chinowsky; 22. Strange particles: production by Cosmotron beams as observed in diffusion cloud chambers William B. Fowler; 23. From the 1940s into the 1950s Abraham Pais; Part VI. Detection of the

  10. Ocean basin volume constraints on global sea level since the Jurassic

    NASA Astrophysics Data System (ADS)

    Seton, M.; Müller, R. D.

    2011-12-01

    Changes in the volume of the ocean basins, predominately via changes in the age-area distribution of oceanic lithosphere, have been suggested as the main driver for long-term eustatic sea-level change. As ocean lithosphere cools and thickens, ocean depth increases. The balance between the abundance of hot and buoyant crust along mid ocean ridges relative to abyssal plains is the primary driving force of long-term sea level changes. The emplacement of volcanic plateaus and chains as well as sedimentation contribute to raising eustatic sea level. Quantifying the average ocean basin depth through time primarily relies on the present day preserved seafloor spreading record, an analysis of the spatio-temporal record of plate boundary processes recorded on the continental margins adjacent to ocean basins as well as a consideration of the rules of plate tectonics, to reconstruct the history of seafloor spreading in the oceanic basins through time. This approach has been successfully applied to predict the magnitude and pattern of eustatic sea-level change since the Cretaceous (Müller et. al. 2008) but uncertainties in reconstructing mid ocean ridges and flanks increase back through time, given that we mainly depend on information preserved in preserved ocean crust. We have reconstructed the age-area distribution of oceanic lithosphere and the plate boundary configurations back to the Jurassic (200 Ma) in order to assess long-term sea-level change from amalgamation to dispersal of Pangaea. We follow the methodology presented in Müller et. al. (2008) but incorporate a new absolute plate motion model derived from Steinberger and Torsvik (2008) prior to 100 Ma, a merged Wessel et. al. (2006) and Wessel and Kroenke (2008) fixed Pacific hotspot reference frame, and a revised model for the formation of Panthalassa and the Cretaceous Pacific. Importantly, we incorporate a model for the break-up of the Ontong Java-Manihiki-Hikurangi plateaus between 120-86 Ma. We extend a

  11. Application of a Multiscale Model of Tantalum Deformation at Megabar Pressures

    SciTech Connect

    Cavallo, R M; Park, H; Barton, N R; Remignton, B A; Pollaine, S M; Prisbrey, S T; Bernier, J V; May, M J; Maddox, B R; Swift, D W; Becker, R C; Olson, R T

    2010-05-13

    thickness indicating that localizations not captured in the overall simulation have probably become dominant, i.e., the target is likely breaking up. Application of the multiscale dislocation dynamics model as implemented in the Ares hydrodynamics code shows excellent agreement with both the pRad and Omega data. They also compare the Steinberg-Lund (SL), Preston-Tonks-Wallace (PTW), and Stainberg-Guinan (SG) models with the data. The PTW and SG models provide good fits to the pRad data but over-predict the growth (underestimate the strength) on the laser platform. The SL model under-predicts the pRad data and over-predicts the Omega data. The excellent agreement of the multiscale model with the data over two orders of magnitude in strain rate and more than a factor of two in pressure lends credibility to the model. They continue to stress the model by conducting experiments at 5 Mbars and beyond at the National Ignition Facility at LLNL in the near future.

  12. Titanium (IV) sol-gel chemistry in varied gravity environments

    NASA Astrophysics Data System (ADS)

    Hales, Matthew; Martens, Wayde; Steinberg, Theodore

    . The test systems and experimental results obtained will be presented. 1. Okubo, T., Tsuchida, A., Okuda, T., Fujitsuna, K., Ishikawa, M., Morita, T., Tada, T. , Kinetic Analyses of Colloidal Crystallization in Microgravity -Aircraft Experiments. . Colloids and Surfaces A: Physicochemical and Engineering Aspects, 1999. 153: p. 515-524. 2. Okubo, T., Tsuchida, A., Kobayashi, K., Kuno, A., Morita, T., Fujishima, M., Kohno, Y., Kinetic Study of the Formation Reaction of Colloidal Silica Spheres in Microgravity Using Aircraft. Colloid Polymer Science, 1999. 277(5): p. 474-478. 3. Pienaar, C.L., Chiffoleau, G. J. A., Follens, L. R. A., Martens, J. A., Kirschhock, C. E. A., Steinberg, T. A., Effect of Gravity on the Gelation of Silica Sols. Chem. Mater., 2007. 19(4): p. 660-664. 4. Smith, D.D., et al., Effect of Microgravity on the Growth of Silica Nanostructures. Langmuir, 2000. 16(26): p. 10055-10060. 5. Zhang, X., Johnson, D.P., Manerbino, A.R., Moore, J.J., Schowengerdt, F. , Recent Mi-crogravity Results in the Synthesis of Porous Materials. AIP Conference Proceedings (Space Technology and Applications International Forum-1999, Pt. 1), 1999. 458: p. 88-93. 6. Dunbar, P.B., Bendzko, N.J.,, 1H and 13C NMR observation of the reaction of acetic acid with titanium isopropoxide. Materials Chemistry and Physics, 1999. 59: p. 26-35. 7. Krunks, M., Oja, I., T˜nsuaadu, K., Es-Souni, M., Gruselle, M., Niinistü,. L, Thermoanalytical study of acetylacetonate-modified titanium (iv) isopropoxide as precursor for TiO2 films. Journal of Thermal Analysis and Calorimetry, 2005: p. 483-488. 8. Moran, P.D., Bowmaker, G. A., Cooney, R. P., Vibrational Spectra and Molecular Associa-tion of Titanium Tetraisopropoxide. Inorg. Chem., 1998. 37(1): p. 2741-2748. 9. Somogyvari, A., Serpone, N.,, Evidence for five-coordination in titanium(1V) complexes. A nuclear magnetic resonance investigation. Canadian Journal of Chemistry, 1977. 56: p. 316-319.

  13. PREFACE: EmQM13: Emergent Quantum Mechanics 2013

    NASA Astrophysics Data System (ADS)

    2014-04-01

    these proceedings represent the talks of the invited speakers as written immediately after the symposium. The volume starts with a contribution by organizers Jan Walleczek and Gerhard Grössing, essentially explaining why emergent quantum mechanics, and other deterministic approaches to quantum theory, must be considered viable approaches in quantum foundations today. This is followed by the exposition of Stephen Adler's talk who introduced to a general audience key questions at the current frontiers of quantum mechanics during the opening evening (with the contents of his conference talk appearing elsewhere). The conference proceedings then continues with the presentations as given in their chronological order i.e. starting with the opening talk of the scientific program by Gerard 't Hooft. While the page number was restricted for all invited speakers, the paper by Jeff Tollaksen was given more space, as his invited collaborator Yakir Aharonov was unable to deliver a separate talk, in order to represent both contributions in one paper. Note that the talks of all speakers, including the talks of those who could not be represented in this volume (M. Arndt, B. Braverman, C. Brukner, S. Colin, Y. Couder, B. Poirier, A. Steinberg, G. Weihs and H. Wiseman) are freely available on the conference website as video presentations (http://www.emqm13.org). The organizers wish to express their gratitude to Siegfried Fussy and Herbert Schwabl from AINS for the organizational support. The organizers also wish to thank Bruce Fetzer, President and CEO, John E. Fetzer Memorial Trust, and the Members of the Board of Trustees, for their strong support and for funding this symposium. We also wish to thank the Austrian Academy of Sciences for allowing the symposium to be held on their premises, and Anton Zeilinger, President of the Austrian Academy of Sciences, for his welcome address. The expertise of the Members of the Scientific Advisory Board of the EmQM13 symposium, Ana Maria Cetto

  14. Humic first, A new theory on the origin of life

    NASA Astrophysics Data System (ADS)

    Daei, Mohammad Ali; Daei, Manijeh

    2016-04-01

    other enantiomers, because their spatial structure dictate, as did so regarding elemental selection. References: 1- Miller, Stanly L." production of amino acid under possible primitive Earth conditions" Science 117:528.(may 1953) 2- Encyclopedia Britannica website "carbonaceous contrite" October 17, 2014 3- Shapiro, Robert " A simpler origin for life" Science American February 12 . 2007 4- Pettit, Robert, "organic matter, humus, humate, humic acid, fulvic acid humin: their importance in soil fertility and plant health" 5- International Humic Substances Society website, " What are humic substances" 6- Humic, Fulvic and microbial balance: organic soil conditioning, by William R. Jackson 1993, pag 165-167 7- Steinberg, Christian E.W "Ecology of humic substances in freshwater-determination from geochemistry to ecological niches" (2003)

  15. PREFACE: Turbulent Mixing and Beyond Turbulent Mixing and Beyond

    NASA Astrophysics Data System (ADS)

    Abarzhi, Snezhana I.; Gauthier, Serge; Rosner, Robert

    2008-10-01

    , Italy) V Steinberg (Weiznmann Institute, Israel) A L Velikovich (Naval Research Laboratory, USA) P K Yeung (Georgia Institute of Technology, USA) F A Williams (University of California at San Diego, USA) We would like to thank all the authors and the referees for their contributions to this Topical Issue and for offering their expertise, time and effort We cordially invite the reader to take a look at this Topical Issue for information on the frontiers of theoretical, numerical and experimental research and technology The Organizing Committee hopes the TMB Conference will serve to advance the state-of-the-art in understanding of fundamental physical properties of turbulent mixing and turbulence in unsteady flows and will have an impact on predictive modeling capabilities, physical description and, ultimately, control of these complex processes Snezhana I Abarzhi, Serge Gauthier, Robert Rosner Chicago, 20 Nov 2008

  16. Life cycle assessment in support of sustainable transportation

    NASA Astrophysics Data System (ADS)

    Eckelman, Matthew J.

    2013-06-01

    cycle GHG and air pollutant emissions. A related study in Toronto on life cycle energy use and GHG emissions for high- and low-density development strategies found a ~60% difference in GHG emissions, largely due to transportation (Norman et al 2006). System dynamics and agent-based models may complement LCA in capturing long-term effects of transportation strategies as they are inherently dynamic (Stepp et al 2009), and can internalize spatially resolved decisions about where to settle and work (Waddell 2002). Transportation planning decisions have both direct and indirect, spatially distributed, often long-term effects on our health and our environment. The accompanying work by Chester et al (2013) provides a well-documented case study that highlights the potential of LCA as a rich source of decision support. References Chester M, Pincetl S, Elizabeth Z, Eisenstein W and Matute J 2013 Infrastructure and automobile shifts: positioning transit to reduce life-cycle environmental impacts for urban sustainability goals Environ. Res. Lett. 8 015041 Chester M V and Horvath A 2009 Environmental assessment of passenger transportation should include infrastructure and supply chains Environ. Res. Lett. 4 024008 Fargione J, Hill J, Tilman D, Polasky S and Hawthorne P 2008 Land clearing and the biofuel carbon debt Science 319 1235-8 Kennedy C, Steinberger J, Gasson B, Hansen Y, Hillman T, Havránek M, Pataki D, Phdungsilp A, Ramaswami A and Mendez G V 2009 Greenhouse gas emissions from global cities Environ. Sci. Technol. 43 7297-302 Kunstler J H 1994 Geography of Nowhere: The Rise and Decline of America's Man-Made Landscape (New York: Free Press) Mashayekh Y, Jaramillo P, Samaras C, Hendrickson C T, Blackhurst M, MacLean H L and Matthews H S 2012 Potentials for sustainable transportation in cities to alleviate climate change impacts Environ. Sci. Technol. 46 2529-37 Mutel C L and Hellweg S 2009 Regionalized life cycle assessment: computational methodology and application to